diff --git a/README.md b/README.md
index acf2b488..be1db26c 100644
--- a/README.md
+++ b/README.md
@@ -103,6 +103,26 @@ client.postStatement(
     .block();
 ```
 
+### Posting a Statement with an attachment
+
+Example:
+
+```java
+client.postStatement(
+    r -> r.statement(s -> s.actor(a -> a.name("A N Other").mbox("mailto:another@example.com"))
+
+        .verb(Verb.ATTEMPTED)
+
+        .activityObject(o -> o.id("https://example.com/activity/simplestatement")
+            .definition(d -> d.addName(Locale.ENGLISH, "Simple Statement")))
+
+        .addAttachment(a -> a.content("Simple attachment").length(17).contentType("text/plain")
+            .usageType(URI.create("https://example.com/attachments/simplestatement"))
+            .addDisplay(Locale.ENGLISH, "text attachment"))
+
+    )).block();
+```
+
 ### Posting Statements
 
 Example:
diff --git a/samples/pom.xml b/samples/pom.xml
index 95cbb6d8..34cfb6fc 100644
--- a/samples/pom.xml
+++ b/samples/pom.xml
@@ -36,6 +36,7 @@
     <!-- Statements Resource -->
     <module>get-statement</module>
     <module>post-statement</module>
+    <module>post-statement-with-attachment</module>
     <module>get-statements</module>
     <module>get-more-statements</module>
     <module>get-voided-statement</module>
diff --git a/samples/post-statement-with-attachment/pom.xml b/samples/post-statement-with-attachment/pom.xml
new file mode 100644
index 00000000..b7115b07
--- /dev/null
+++ b/samples/post-statement-with-attachment/pom.xml
@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <parent>
+    <groupId>dev.learning.xapi.samples</groupId>
+    <artifactId>xapi-samples-build</artifactId>
+    <version>1.1.2-SNAPSHOT</version>
+  </parent>
+  <artifactId>post-statement-with-attachment</artifactId>
+  <name>Post xAPI Statement With Attachment Sample</name>
+  <description>Post xAPI Statement With Attachment</description>
+  <dependencies>
+    <dependency>
+      <groupId>dev.learning.xapi</groupId>
+      <artifactId>xapi-client</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>dev.learning.xapi.samples</groupId>
+      <artifactId>core</artifactId>
+    </dependency>
+  </dependencies>
+</project>
diff --git a/samples/post-statement-with-attachment/src/main/java/dev/learning/xapi/samples/poststatement/PostStatementWithAttachmentApplication.java b/samples/post-statement-with-attachment/src/main/java/dev/learning/xapi/samples/poststatement/PostStatementWithAttachmentApplication.java
new file mode 100644
index 00000000..af2e0740
--- /dev/null
+++ b/samples/post-statement-with-attachment/src/main/java/dev/learning/xapi/samples/poststatement/PostStatementWithAttachmentApplication.java
@@ -0,0 +1,78 @@
+/*
+ * Copyright 2016-2023 Berry Cloud Ltd. All rights reserved.
+ */
+
+package dev.learning.xapi.samples.poststatement;
+
+import dev.learning.xapi.client.XapiClient;
+import dev.learning.xapi.model.Verb;
+import java.net.URI;
+import java.nio.file.Files;
+import java.util.Locale;
+import java.util.UUID;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.CommandLineRunner;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.http.ResponseEntity;
+import org.springframework.util.ResourceUtils;
+
+/**
+ * Sample using xAPI client to post a statement with attachments.
+ *
+ * @author Thomas Turrell-Croft
+ * @author István Rátkai (Selindek)
+ */
+@SpringBootApplication
+public class PostStatementWithAttachmentApplication implements CommandLineRunner {
+
+  /**
+   * Default xAPI client. Properties are picked automatically from application.properties.
+   */
+  @Autowired
+  private XapiClient client;
+
+  public static void main(String[] args) {
+    SpringApplication.run(PostStatementWithAttachmentApplication.class, args).close();
+  }
+
+  @Override
+  public void run(String... args) throws Exception {
+    
+    // Load jpg attachment from class-path
+    var data = Files.readAllBytes(ResourceUtils.getFile("classpath:example.jpg").toPath());
+
+    // Post a statement
+    ResponseEntity<
+        UUID> response =
+            client
+                .postStatement(r -> r.statement(
+                    s -> s.actor(a -> a.name("A N Other").mbox("mailto:another@example.com"))
+
+                        .verb(Verb.ATTEMPTED)
+
+                        .activityObject(o -> o.id("https://example.com/activity/simplestatement")
+                            .definition(d -> d.addName(Locale.ENGLISH, "Simple Statement")))
+                        
+                        // Add simple text attachment
+                        .addAttachment(a -> a.content("Simple attachment").length(17)
+                            .contentType("text/plain")
+                            .usageType(URI.create("https://example.com/attachments/greeting"))
+                            .addDisplay(Locale.ENGLISH, "text attachment"))
+
+                        // Add binary attachment
+                        .addAttachment(a -> a.content(data).length(data.length)
+                            .contentType("image/jpeg")
+                            .usageType(URI.create("https://example.com/attachments/greeting"))
+                            .addDisplay(Locale.ENGLISH, "JPEG attachment"))
+                        
+                    )).block();
+
+    // If any attachment with actual data was added to any statement in a request, then it is sent
+    // as a multipart/mixed request automatically instead of the standard application/json format
+    
+    // Print the statementId of the newly created statement to the console
+    System.out.println("StatementId " + response.getBody());
+  }
+
+}
diff --git a/samples/post-statement-with-attachment/src/main/resources/application.properties b/samples/post-statement-with-attachment/src/main/resources/application.properties
new file mode 100644
index 00000000..de20217a
--- /dev/null
+++ b/samples/post-statement-with-attachment/src/main/resources/application.properties
@@ -0,0 +1,3 @@
+xapi.client.username = admin
+xapi.client.password = password
+xapi.client.baseUrl = https://example.com/xapi/
diff --git a/samples/post-statement-with-attachment/src/main/resources/example.jpg b/samples/post-statement-with-attachment/src/main/resources/example.jpg
new file mode 100644
index 00000000..82123354
Binary files /dev/null and b/samples/post-statement-with-attachment/src/main/resources/example.jpg differ
diff --git a/xapi-client/src/main/java/dev/learning/xapi/client/MultipartService.java b/xapi-client/src/main/java/dev/learning/xapi/client/MultipartService.java
new file mode 100644
index 00000000..8e5bb97e
--- /dev/null
+++ b/xapi-client/src/main/java/dev/learning/xapi/client/MultipartService.java
@@ -0,0 +1,191 @@
+/*
+ * Copyright 2016-2023 Berry Cloud Ltd. All rights reserved.
+ */
+
+package dev.learning.xapi.client;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import dev.learning.xapi.model.Attachment;
+import dev.learning.xapi.model.Statement;
+import dev.learning.xapi.model.SubStatement;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.MediaType;
+import org.springframework.util.FastByteArrayOutputStream;
+import org.springframework.web.reactive.function.client.WebClient.RequestBodySpec;
+
+/**
+ * Helper methods for creating multipart message from statements.
+ *
+ * @author István Rátkai (Selindek)
+ */
+@Slf4j
+@RequiredArgsConstructor
+public final class MultipartService {
+
+  private static final String MULTIPART_BOUNDARY = "xapi-learning-dev-boundary";
+  private static final String MULTIPART_CONTENT_TYPE = "multipart/mixed; boundary="
+      + MULTIPART_BOUNDARY;
+  private static final String CRLF = "\r\n";
+  private static final String BOUNDARY_PREFIX = "--";
+  private static final String BODY_SEPARATOR = BOUNDARY_PREFIX + MULTIPART_BOUNDARY + CRLF;
+  private static final String BODY_FOOTER = BOUNDARY_PREFIX + MULTIPART_BOUNDARY + BOUNDARY_PREFIX;
+  private static final String CONTENT_TYPE = HttpHeaders.CONTENT_TYPE + ":";
+
+  private static final byte[] BA_APP_JSON_HEADER = (CONTENT_TYPE + MediaType.APPLICATION_JSON_VALUE
+      + CRLF + CRLF).getBytes(StandardCharsets.UTF_8);
+  private static final byte[] BA_CRLF = CRLF.getBytes(StandardCharsets.UTF_8);
+  private static final byte[] BA_BODY_SEPARATOR = BODY_SEPARATOR.getBytes(StandardCharsets.UTF_8);
+  private static final byte[] BA_BODY_FOOTER = BODY_FOOTER.getBytes(StandardCharsets.UTF_8);
+  private static final byte[] BA_CONTENT_TYPE = CONTENT_TYPE.getBytes(StandardCharsets.UTF_8);
+  private static final byte[] BA_ENCODING_HEADER = ("Content-Transfer-Encoding:binary" + CRLF)
+      .getBytes(StandardCharsets.UTF_8);
+  private static final byte[] BA_X_API_HASH = "X-Experience-API-Hash:"
+      .getBytes(StandardCharsets.UTF_8);
+
+  public static final MediaType MULTIPART_MEDIATYPE = MediaType.valueOf(MULTIPART_CONTENT_TYPE);
+
+  private final ObjectMapper objectMapper;
+
+  /**
+   * <p>
+   * Add a Statement to the request.
+   * </p>
+   * This method adds the statement and its attachments if there are any to the request body. Also
+   * sets the content-type to multipart/mixed if needed.
+   *
+   * @param requestSpec a {@link RequestBodySpec} object.
+   * @param statement   a {@link Statement} to add.
+   */
+  public void addBody(RequestBodySpec requestSpec, Statement statement) {
+
+    addBody(requestSpec, statement, getRealAttachments(statement));
+
+  }
+
+  /**
+   * <p>
+   * Adds a List of {@link Statement}s to the request.
+   * </p>
+   * This method adds the statements and their attachments if there are any to the request body.
+   * Also sets the content-type to multipart/mixed if needed.
+   *
+   * @param requestSpec a {@link RequestBodySpec} object.
+   * @param statements  list of {@link Statement}s to add.
+   */
+  public void addBody(RequestBodySpec requestSpec, List<Statement> statements) {
+
+    addBody(requestSpec, statements, statements.stream().flatMap(this::getRealAttachments));
+
+  }
+
+  private void addBody(RequestBodySpec requestSpec, Object statements,
+      Stream<Attachment> attachments) {
+
+    final var attachmentsBody = writeAttachments(attachments);
+
+    if (attachmentsBody.length == 0) {
+      // add body directly, content-type is default application/json
+      requestSpec.bodyValue(statements);
+    } else {
+      // has at least one attachment with actual data -> set content-type
+      requestSpec.contentType(MULTIPART_MEDIATYPE);
+      // construct whole multipart body manually
+      requestSpec.bodyValue(createMultipartBody(statements, attachmentsBody));
+    }
+
+  }
+
+  /**
+   * Gets {@link Attachment}s of a {@link Statement} which has data property as a {@link Stream}.
+   *
+   * @param statement a {@link Statement} object
+   * @return {@link Attachment} of a {@link Statement} which has data property as a {@link Stream}.
+   */
+  private Stream<Attachment> getRealAttachments(Statement statement) {
+
+    // handle the rare scenario when a sub-statement has an attachment
+    Stream<Attachment> stream = statement.getObject() instanceof final SubStatement substatement
+        && substatement.getAttachments() != null ? substatement.getAttachments().stream()
+            : Stream.empty();
+
+    if (statement.getAttachments() != null) {
+      stream = Stream.concat(stream, statement.getAttachments().stream());
+    }
+
+    return stream.filter(a -> a.getContent() != null);
+  }
+
+  private byte[] createMultipartBody(Object statements, byte[] attachments) {
+
+    try (var stream = new FastByteArrayOutputStream()) {
+      // Multipart Boundary
+      stream.write(BA_BODY_SEPARATOR);
+
+      // Header of first part
+      stream.write(BA_APP_JSON_HEADER);
+
+      // Body of first part
+      stream.write(objectMapper.writeValueAsBytes(statements));
+      stream.write(BA_CRLF);
+
+      // Body of attachments
+      stream.write(attachments);
+
+      // Footer
+      stream.write(BA_BODY_FOOTER);
+
+      return stream.toByteArrayUnsafe();
+    } catch (final IOException e) {
+      log.error("Cannot create multipart body", e);
+      return new byte[] {};
+    }
+  }
+
+  /*
+   * Writes attachments to a byte array. If there are no attachments in the stream then returns an
+   * empty array.
+   */
+  private static byte[] writeAttachments(Stream<Attachment> attachments) {
+
+    try (var stream = new FastByteArrayOutputStream()) {
+
+      // Write each sha2-identical attachments only once
+      attachments.collect(Collectors.toMap(Attachment::getSha2, v -> v, (k, v) -> v)).values()
+          .forEach(a -> {
+            try {
+              // Multipart Boundary
+              stream.write(BA_BODY_SEPARATOR);
+
+              // Multipart headers
+              stream.write(BA_CONTENT_TYPE);
+              stream.write(a.getContentType().getBytes(StandardCharsets.UTF_8));
+              stream.write(BA_CRLF);
+
+              stream.write(BA_ENCODING_HEADER);
+
+              stream.write(BA_X_API_HASH);
+              stream.write(a.getSha2().getBytes(StandardCharsets.UTF_8));
+              stream.write(BA_CRLF);
+              stream.write(BA_CRLF);
+
+              // Multipart body
+              stream.write(a.getContent());
+              stream.write(BA_CRLF);
+            } catch (final IOException e) {
+              log.error("Cannot create multipart body", e);
+            }
+
+          });
+
+      return stream.toByteArrayUnsafe();
+    }
+  }
+
+}
diff --git a/xapi-client/src/main/java/dev/learning/xapi/client/XapiClient.java b/xapi-client/src/main/java/dev/learning/xapi/client/XapiClient.java
index 0b1dc139..5b9aa3ff 100644
--- a/xapi-client/src/main/java/dev/learning/xapi/client/XapiClient.java
+++ b/xapi-client/src/main/java/dev/learning/xapi/client/XapiClient.java
@@ -4,6 +4,7 @@
 
 package dev.learning.xapi.client;
 
+import com.fasterxml.jackson.databind.ObjectMapper;
 import dev.learning.xapi.model.About;
 import dev.learning.xapi.model.Activity;
 import dev.learning.xapi.model.Person;
@@ -25,7 +26,6 @@
  *
  * @author Thomas Turrell-Croft
  * @author István Rátkai (Selindek)
- *
  * @see <a href=
  *      "https://github.com/adlnet/xAPI-Spec/blob/master/xAPI-Communication.md#20-resources">xAPI
  *      communication resources</a>
@@ -33,20 +33,24 @@
 public class XapiClient {
 
   private final WebClient webClient;
+  private final MultipartService multipartService;
 
-  private static final ParameterizedTypeReference<List<UUID>> LIST_UUID_TYPE =
-      new ParameterizedTypeReference<>() {};
+  private static final ParameterizedTypeReference<
+      List<UUID>> LIST_UUID_TYPE = new ParameterizedTypeReference<>() {
+      };
 
-  private static final ParameterizedTypeReference<List<String>> LIST_STRING_TYPE =
-      new ParameterizedTypeReference<>() {};
+  private static final ParameterizedTypeReference<
+      List<String>> LIST_STRING_TYPE = new ParameterizedTypeReference<>() {
+      };
 
   /**
    * Default constructor for XapiClient.
    *
    * @param builder a {@link WebClient.Builder} object. The caller must set the baseUrl and the
-   *        authorization header.
+   *                authorization header.
    */
-  public XapiClient(WebClient.Builder builder) {
+  public XapiClient(WebClient.Builder builder, ObjectMapper objectMapper) {
+    this.multipartService = new MultipartService(objectMapper);
     this.webClient = builder
 
         .defaultHeader("X-Experience-API-Version", "1.0.3")
@@ -111,15 +115,15 @@ public Mono<ResponseEntity<UUID>> postStatement(PostStatementRequest request) {
 
     final Map<String, Object> queryParams = new HashMap<>();
 
-    return this.webClient
+    final var requestSpec = this.webClient
 
         .method(request.getMethod())
 
-        .uri(u -> request.url(u, queryParams).build(queryParams))
+        .uri(u -> request.url(u, queryParams).build(queryParams));
 
-        .bodyValue(request.getStatement())
+    multipartService.addBody(requestSpec, request.getStatement());
 
-        .retrieve()
+    return requestSpec.retrieve()
 
         .toEntity(LIST_UUID_TYPE)
 
@@ -158,15 +162,15 @@ public Mono<ResponseEntity<List<UUID>>> postStatements(PostStatementsRequest req
 
     final Map<String, Object> queryParams = new HashMap<>();
 
-    return this.webClient
+    final var requestSpec = this.webClient
 
         .method(request.getMethod())
 
-        .uri(u -> request.url(u, queryParams).build(queryParams))
+        .uri(u -> request.url(u, queryParams).build(queryParams));
 
-        .bodyValue(request.getStatements())
+    multipartService.addBody(requestSpec, request.getStatements());
 
-        .retrieve()
+    return requestSpec.retrieve()
 
         .toEntity(LIST_UUID_TYPE);
 
@@ -257,7 +261,6 @@ public Mono<ResponseEntity<StatementResult>> getStatements() {
    * </p>
    *
    * @param request The parameters of the get statements request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<StatementResult>> getStatements(GetStatementsRequest request) {
@@ -284,7 +287,6 @@ public Mono<ResponseEntity<StatementResult>> getStatements(GetStatementsRequest
    * </p>
    *
    * @param request The Consumer Builder for the get statements request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<StatementResult>> getStatements(
@@ -306,7 +308,6 @@ public Mono<ResponseEntity<StatementResult>> getStatements(
    * </p>
    *
    * @param request The parameters of the get more statements request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<StatementResult>> getMoreStatements(GetMoreStatementsRequest request) {
@@ -333,7 +334,6 @@ public Mono<ResponseEntity<StatementResult>> getMoreStatements(GetMoreStatements
    * </p>
    *
    * @param request The Consumer Builder for the get more statements request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<StatementResult>> getMoreStatements(
@@ -357,7 +357,6 @@ public Mono<ResponseEntity<StatementResult>> getMoreStatements(
    * </p>
    *
    * @param request The parameters of the get state request
-   *
    * @return the ResponseEntity
    */
   public <T> Mono<ResponseEntity<T>> getState(GetStateRequest request, Class<T> bodyType) {
@@ -384,7 +383,6 @@ public <T> Mono<ResponseEntity<T>> getState(GetStateRequest request, Class<T> bo
    * </p>
    *
    * @param request The Consumer Builder for the get state request
-   *
    * @return the ResponseEntity
    */
   public <T> Mono<ResponseEntity<T>> getState(Consumer<GetStateRequest.Builder<?, ?>> request,
@@ -406,7 +404,6 @@ public <T> Mono<ResponseEntity<T>> getState(Consumer<GetStateRequest.Builder<?,
    * </p>
    *
    * @param request The parameters of the post state request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Void>> postState(PostStateRequest request) {
@@ -437,7 +434,6 @@ public Mono<ResponseEntity<Void>> postState(PostStateRequest request) {
    * </p>
    *
    * @param request The Consumer Builder for the post state request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Void>> postState(Consumer<PostStateRequest.Builder<?, ?>> request) {
@@ -458,7 +454,6 @@ public Mono<ResponseEntity<Void>> postState(Consumer<PostStateRequest.Builder<?,
    * </p>
    *
    * @param request The parameters of the put state request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Void>> putState(PutStateRequest request) {
@@ -489,7 +484,6 @@ public Mono<ResponseEntity<Void>> putState(PutStateRequest request) {
    * </p>
    *
    * @param request The Consumer Builder for the put state request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Void>> putState(Consumer<PutStateRequest.Builder<?, ?>> request) {
@@ -510,7 +504,6 @@ public Mono<ResponseEntity<Void>> putState(Consumer<PutStateRequest.Builder<?, ?
    * </p>
    *
    * @param request The parameters of the delete state request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Void>> deleteState(DeleteStateRequest request) {
@@ -537,7 +530,6 @@ public Mono<ResponseEntity<Void>> deleteState(DeleteStateRequest request) {
    * </p>
    *
    * @param request The Consumer Builder for the delete state request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Void>> deleteState(
@@ -556,7 +548,6 @@ public Mono<ResponseEntity<Void>> deleteState(
    * parameters.
    *
    * @param request The parameters of the get states request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<List<String>>> getStates(GetStatesRequest request) {
@@ -583,7 +574,6 @@ public Mono<ResponseEntity<List<String>>> getStates(GetStatesRequest request) {
    * </p>
    *
    * @param request The Consumer Builder for the get states request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<List<String>>> getStates(
@@ -604,7 +594,6 @@ public Mono<ResponseEntity<List<String>>> getStates(
    * </p>
    *
    * @param request The parameters of the delete states request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Void>> deleteStates(DeleteStatesRequest request) {
@@ -630,7 +619,6 @@ public Mono<ResponseEntity<Void>> deleteStates(DeleteStatesRequest request) {
    * </p>
    *
    * @param request The Consumer Builder for the delete states request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Void>> deleteStates(
@@ -652,7 +640,6 @@ public Mono<ResponseEntity<Void>> deleteStates(
    * value, and it is legal to include multiple identifying properties.
    *
    * @param request The parameters of the get agents request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Person>> getAgents(GetAgentsRequest request) {
@@ -677,7 +664,6 @@ public Mono<ResponseEntity<Person>> getAgents(GetAgentsRequest request) {
    * value, and it is legal to include multiple identifying properties.
    *
    * @param request The Consumer Builder for the get agents request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Person>> getAgents(Consumer<GetAgentsRequest.Builder> request) {
@@ -696,7 +682,6 @@ public Mono<ResponseEntity<Person>> getAgents(Consumer<GetAgentsRequest.Builder>
    * Loads the complete Activity Object specified.
    *
    * @param request The parameters of the get activity request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Activity>> getActivity(GetActivityRequest request) {
@@ -719,7 +704,6 @@ public Mono<ResponseEntity<Activity>> getActivity(GetActivityRequest request) {
    * Loads the complete Activity Object specified.
    *
    * @param request The Consumer Builder for the get activity request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Activity>> getActivity(Consumer<GetActivityRequest.Builder> request) {
@@ -741,7 +725,6 @@ public Mono<ResponseEntity<Activity>> getActivity(Consumer<GetActivityRequest.Bu
    * </p>
    *
    * @param request The parameters of the get agent profile request
-   *
    * @return the ResponseEntity
    */
   public <T> Mono<ResponseEntity<T>> getAgentProfile(GetAgentProfileRequest request,
@@ -768,7 +751,6 @@ public <T> Mono<ResponseEntity<T>> getAgentProfile(GetAgentProfileRequest reques
    * </p>
    *
    * @param request The Consumer Builder for the get agent profile request
-   *
    * @return the ResponseEntity
    */
   public <T> Mono<ResponseEntity<T>> getAgentProfile(
@@ -789,7 +771,6 @@ public <T> Mono<ResponseEntity<T>> getAgentProfile(
    * </p>
    *
    * @param request The parameters of the delete agent profile request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Void>> deleteAgentProfile(DeleteAgentProfileRequest request) {
@@ -815,7 +796,6 @@ public Mono<ResponseEntity<Void>> deleteAgentProfile(DeleteAgentProfileRequest r
    * </p>
    *
    * @param request The Consumer Builder for the delete agent profile request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Void>> deleteAgentProfile(
@@ -836,7 +816,6 @@ public Mono<ResponseEntity<Void>> deleteAgentProfile(
    * </p>
    *
    * @param request The parameters of the put agent profile request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Void>> putAgentProfile(PutAgentProfileRequest request) {
@@ -866,7 +845,6 @@ public Mono<ResponseEntity<Void>> putAgentProfile(PutAgentProfileRequest request
    * </p>
    *
    * @param request The Consumer Builder for the put agent profile request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Void>> putAgentProfile(
@@ -887,7 +865,6 @@ public Mono<ResponseEntity<Void>> putAgentProfile(
    * </p>
    *
    * @param request The parameters of the post agent profile request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Void>> postAgentProfile(PostAgentProfileRequest request) {
@@ -917,7 +894,6 @@ public Mono<ResponseEntity<Void>> postAgentProfile(PostAgentProfileRequest reque
    * </p>
    *
    * @param request The Consumer Builder for the post agent profile request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Void>> postAgentProfile(
@@ -937,7 +913,6 @@ public Mono<ResponseEntity<Void>> postAgentProfile(
    * (exclusive).
    *
    * @param request The parameters of the get agent profiles request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<List<String>>> getAgentProfiles(GetAgentProfilesRequest request) {
@@ -962,7 +937,6 @@ public Mono<ResponseEntity<List<String>>> getAgentProfiles(GetAgentProfilesReque
    * (exclusive).
    *
    * @param request The Consumer Builder for the get agent profiles request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<List<String>>> getAgentProfiles(
@@ -985,7 +959,6 @@ public Mono<ResponseEntity<List<String>>> getAgentProfiles(
    * </p>
    *
    * @param request The parameters of the get activity profile request
-   *
    * @return the ResponseEntity
    */
   public <T> Mono<ResponseEntity<T>> getActivityProfile(GetActivityProfileRequest request,
@@ -1012,7 +985,6 @@ public <T> Mono<ResponseEntity<T>> getActivityProfile(GetActivityProfileRequest
    * </p>
    *
    * @param request The Consumer Builder for the get activity profile request
-   *
    * @return the ResponseEntity
    */
   public <T> Mono<ResponseEntity<T>> getActivityProfile(
@@ -1033,7 +1005,6 @@ public <T> Mono<ResponseEntity<T>> getActivityProfile(
    * </p>
    *
    * @param request The parameters of the post activity profile request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Void>> postActivityProfile(PostActivityProfileRequest request) {
@@ -1063,7 +1034,6 @@ public Mono<ResponseEntity<Void>> postActivityProfile(PostActivityProfileRequest
    * </p>
    *
    * @param request The Consumer Builder for the post activity profile request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Void>> postActivityProfile(
@@ -1084,7 +1054,6 @@ public Mono<ResponseEntity<Void>> postActivityProfile(
    * </p>
    *
    * @param request The parameters of the put activity profile request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Void>> putActivityProfile(PutActivityProfileRequest request) {
@@ -1114,7 +1083,6 @@ public Mono<ResponseEntity<Void>> putActivityProfile(PutActivityProfileRequest r
    * </p>
    *
    * @param request The Consumer Builder for the put activity profile request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Void>> putActivityProfile(
@@ -1135,7 +1103,6 @@ public Mono<ResponseEntity<Void>> putActivityProfile(
    * </p>
    *
    * @param request The parameters of the delete activity profile request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Void>> deleteActivityProfile(DeleteActivityProfileRequest request) {
@@ -1161,14 +1128,13 @@ public Mono<ResponseEntity<Void>> deleteActivityProfile(DeleteActivityProfileReq
    * </p>
    *
    * @param request The Consumer Builder for the delete activity profile request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<Void>> deleteActivityProfile(
       Consumer<DeleteActivityProfileRequest.Builder<?, ?>> request) {
 
-    final DeleteActivityProfileRequest.Builder<?, ?> builder =
-        DeleteActivityProfileRequest.builder();
+    final DeleteActivityProfileRequest.Builder<?,
+        ?> builder = DeleteActivityProfileRequest.builder();
 
     request.accept(builder);
 
@@ -1185,7 +1151,6 @@ public Mono<ResponseEntity<Void>> deleteActivityProfile(
    * </p>
    *
    * @param request The parameters of the get activity profiles request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<List<String>>> getActivityProfiles(
@@ -1214,7 +1179,6 @@ public Mono<ResponseEntity<List<String>>> getActivityProfiles(
    * </p>
    *
    * @param request The Consumer Builder for the get activity profiles request
-   *
    * @return the ResponseEntity
    */
   public Mono<ResponseEntity<List<String>>> getActivityProfiles(
diff --git a/xapi-client/src/main/java/dev/learning/xapi/client/configuration/XapiClientAutoConfiguration.java b/xapi-client/src/main/java/dev/learning/xapi/client/configuration/XapiClientAutoConfiguration.java
index ab2438ac..9e83e8fd 100644
--- a/xapi-client/src/main/java/dev/learning/xapi/client/configuration/XapiClientAutoConfiguration.java
+++ b/xapi-client/src/main/java/dev/learning/xapi/client/configuration/XapiClientAutoConfiguration.java
@@ -4,6 +4,7 @@
 
 package dev.learning.xapi.client.configuration;
 
+import com.fasterxml.jackson.databind.ObjectMapper;
 import dev.learning.xapi.client.XapiClient;
 import java.util.List;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
@@ -28,7 +29,7 @@ public class XapiClientAutoConfiguration {
   @Bean
   @ConditionalOnMissingBean
   public XapiClient xapiClient(XapiClientProperties properties, WebClient.Builder builder,
-      List<XapiClientConfigurer> configurers) {
+      List<XapiClientConfigurer> configurers, ObjectMapper objectMapper) {
 
     if (properties.getAuthorization() != null) {
       builder.defaultHeader(HttpHeaders.AUTHORIZATION, properties.getAuthorization());
@@ -44,7 +45,7 @@ public XapiClient xapiClient(XapiClientProperties properties, WebClient.Builder
 
     configurers.forEach(c -> c.accept(builder));
 
-    return new XapiClient(builder);
+    return new XapiClient(builder, objectMapper);
 
   }
 
diff --git a/xapi-client/src/test/java/dev/learning/xapi/client/XapiClientMultipartTests.java b/xapi-client/src/test/java/dev/learning/xapi/client/XapiClientMultipartTests.java
new file mode 100644
index 00000000..c89b9666
--- /dev/null
+++ b/xapi-client/src/test/java/dev/learning/xapi/client/XapiClientMultipartTests.java
@@ -0,0 +1,305 @@
+/*
+ * Copyright 2016rue-2023 Berry Cloud Ltd. All rights reserved.
+ */
+package dev.learning.xapi.client;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.core.Is.is;
+import static org.hamcrest.core.StringStartsWith.startsWith;
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import dev.learning.xapi.model.Activity;
+import dev.learning.xapi.model.Agent;
+import dev.learning.xapi.model.Statement;
+import dev.learning.xapi.model.SubStatement;
+import dev.learning.xapi.model.Verb;
+import java.net.URI;
+import java.time.Instant;
+import java.util.Locale;
+import okhttp3.mockwebserver.MockResponse;
+import okhttp3.mockwebserver.MockWebServer;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.web.reactive.function.client.WebClient;
+
+/**
+ * XapiClient Tests.
+ *
+ * @author Thomas Turrell-Croft
+ */
+@DisplayName("XapiClient Tests")
+@SpringBootTest
+class XapiClientMultipartTests {
+
+  @Autowired
+  private WebClient.Builder webClientBuilder;
+
+  @Autowired
+  private ObjectMapper objectMapper;
+
+  private MockWebServer mockWebServer;
+  private XapiClient client;
+
+  @BeforeEach
+  void setUp() throws Exception {
+    mockWebServer = new MockWebServer();
+    mockWebServer.start();
+
+    webClientBuilder.baseUrl(mockWebServer.url("").toString());
+
+    client = new XapiClient(webClientBuilder, objectMapper);
+
+  }
+
+  @AfterEach
+  void tearDown() throws Exception {
+    mockWebServer.shutdown();
+  }
+
+  @Test
+  void whenPostingStatementWithAttachmentThenContentTypeHeaderIsMultipartMixed()
+      throws InterruptedException {
+
+    mockWebServer.enqueue(new MockResponse().setStatus("HTTP/1.1 200 OK")
+        .setBody("[\"19a74a3f-7354-4254-aa4a-1c39ab4f2ca7\"]")
+        .setHeader("Content-Type", "application/json"));
+
+    // When Posting Statement With Attachment
+    client.postStatement(
+        r -> r.statement(s -> s.actor(a -> a.name("A N Other").mbox("mailto:another@example.com"))
+
+            .addAttachment(a -> a.content("Simple attachment").length(17).contentType("text/plain")
+                .usageType(URI.create("http://adlnet.gov/expapi/attachments/text"))
+                .addDisplay(Locale.ENGLISH, "text attachment"))
+
+            .verb(Verb.ATTEMPTED)
+
+            .activityObject(o -> o.id("https://example.com/activity/simplestatement")
+                .definition(d -> d.addName(Locale.ENGLISH, "Simple Statement")))))
+        .block();
+
+    final var recordedRequest = mockWebServer.takeRequest();
+
+    // Then Content Type Header Is Multipart Mixed
+    assertThat(recordedRequest.getHeader("content-type"), startsWith("multipart/mixed"));
+  }
+
+  @Test
+  void whenPostingStatementWithTextAttachmentThenBodyIsExpected() throws InterruptedException {
+
+    mockWebServer.enqueue(new MockResponse().setStatus("HTTP/1.1 200 OK")
+        .setBody("[\"19a74a3f-7354-4254-aa4a-1c39ab4f2ca7\"]")
+        .setHeader("Content-Type", "application/json"));
+
+    // When Posting Statement With Text Attachment
+    client.postStatement(
+        r -> r.statement(s -> s.actor(a -> a.name("A N Other").mbox("mailto:another@example.com"))
+
+            .addAttachment(a -> a.content("Simple attachment").length(17).contentType("text/plain")
+                .usageType(URI.create("http://adlnet.gov/expapi/attachments/text"))
+                .addDisplay(Locale.ENGLISH, "text attachment"))
+
+            .verb(Verb.ATTEMPTED)
+
+            .activityObject(o -> o.id("https://example.com/activity/simplestatement")
+                .definition(d -> d.addName(Locale.ENGLISH, "Simple Statement")))))
+        .block();
+
+    final var recordedRequest = mockWebServer.takeRequest();
+
+    // Then Body Is Expected
+    assertThat(recordedRequest.getBody().readUtf8(), is(
+        "--xapi-learning-dev-boundary\r\nContent-Type:application/json\r\n\r\n{\"actor\":{\"objectType\":\"Agent\",\"name\":\"A N Other\",\"mbox\":\"mailto:another@example.com\"},\"verb\":{\"id\":\"http://adlnet.gov/expapi/verbs/attempted\",\"display\":{\"und\":\"attempted\"}},\"object\":{\"objectType\":\"Activity\",\"id\":\"https://example.com/activity/simplestatement\",\"definition\":{\"name\":{\"en\":\"Simple Statement\"}}},\"attachments\":[{\"usageType\":\"http://adlnet.gov/expapi/attachments/text\",\"display\":{\"en\":\"text attachment\"},\"contentType\":\"text/plain\",\"length\":17,\"sha2\":\"b154d3fd46a5068da42ba05a8b9c971688ab5a57eb5c3a0e50a23c42a86786e5\"}]}\r\n--xapi-learning-dev-boundary\r\nContent-Type:text/plain\r\nContent-Transfer-Encoding:binary\r\nX-Experience-API-Hash:b154d3fd46a5068da42ba05a8b9c971688ab5a57eb5c3a0e50a23c42a86786e5\r\n\r\nSimple attachment\r\n--xapi-learning-dev-boundary--"));
+  }
+
+  @Test
+  void whenPostingStatementWithBinaryAttachmentThenBodyIsExpected() throws InterruptedException {
+
+    mockWebServer.enqueue(new MockResponse().setStatus("HTTP/1.1 200 OK")
+        .setBody("[\"19a74a3f-7354-4254-aa4a-1c39ab4f2ca7\"]")
+        .setHeader("Content-Type", "application/json"));
+
+    // When Posting Statement With Binary Attachment
+    client.postStatement(
+        r -> r.statement(s -> s.actor(a -> a.name("A N Other").mbox("mailto:another@example.com"))
+
+            .addAttachment(a -> a.content(new byte[] {64, 65, 66, 67, 68, (byte) 255}).length(6)
+                .contentType("application/octet-stream")
+                .usageType(URI.create("http://adlnet.gov/expapi/attachments/code"))
+                .addDisplay(Locale.ENGLISH, "binary attachment"))
+
+            .verb(Verb.ATTEMPTED)
+
+            .activityObject(o -> o.id("https://example.com/activity/simplestatement")
+                .definition(d -> d.addName(Locale.ENGLISH, "Simple Statement")))))
+        .block();
+
+    final var recordedRequest = mockWebServer.takeRequest();
+
+    // Then Body Is Expected
+    assertThat(recordedRequest.getBody().readUtf8(), is(
+        "--xapi-learning-dev-boundary\r\nContent-Type:application/json\r\n\r\n{\"actor\":{\"objectType\":\"Agent\",\"name\":\"A N Other\",\"mbox\":\"mailto:another@example.com\"},\"verb\":{\"id\":\"http://adlnet.gov/expapi/verbs/attempted\",\"display\":{\"und\":\"attempted\"}},\"object\":{\"objectType\":\"Activity\",\"id\":\"https://example.com/activity/simplestatement\",\"definition\":{\"name\":{\"en\":\"Simple Statement\"}}},\"attachments\":[{\"usageType\":\"http://adlnet.gov/expapi/attachments/code\",\"display\":{\"en\":\"binary attachment\"},\"contentType\":\"application/octet-stream\",\"length\":6,\"sha2\":\"0f4b9b79ad9e0572dbc7ce7d4dd38b96dc66d28ca87d7fd738ec8f9a30935bf6\"}]}\r\n--xapi-learning-dev-boundary\r\nContent-Type:application/octet-stream\r\nContent-Transfer-Encoding:binary\r\nX-Experience-API-Hash:0f4b9b79ad9e0572dbc7ce7d4dd38b96dc66d28ca87d7fd738ec8f9a30935bf6\r\n\r\n@ABCD�\r\n--xapi-learning-dev-boundary--"));
+  }
+
+  @Test
+  void whenPostingStatementWithoutAttachmentDataThenBodyIsExpected() throws InterruptedException {
+
+    mockWebServer.enqueue(new MockResponse().setStatus("HTTP/1.1 200 OK")
+        .setBody("[\"19a74a3f-7354-4254-aa4a-1c39ab4f2ca7\"]")
+        .setHeader("Content-Type", "application/json"));
+
+    // When Posting Statement Without Attachment Data
+    client.postStatement(
+        r -> r.statement(s -> s.actor(a -> a.name("A N Other").mbox("mailto:another@example.com"))
+
+            .addAttachment(a -> a.length(6).contentType("application/octet-stream")
+                .usageType(URI.create("http://adlnet.gov/expapi/attachments/code"))
+                .fileUrl(URI.create("example.com/attachment"))
+                .addDisplay(Locale.ENGLISH, "binary attachment"))
+
+            .verb(Verb.ATTEMPTED)
+
+            .activityObject(o -> o.id("https://example.com/activity/simplestatement")
+                .definition(d -> d.addName(Locale.ENGLISH, "Simple Statement")))))
+        .block();
+
+    final var recordedRequest = mockWebServer.takeRequest();
+
+    // Then Body Is Expected
+    assertThat(recordedRequest.getBody().readUtf8(), is(
+        "{\"actor\":{\"objectType\":\"Agent\",\"name\":\"A N Other\",\"mbox\":\"mailto:another@example.com\"},\"verb\":{\"id\":\"http://adlnet.gov/expapi/verbs/attempted\",\"display\":{\"und\":\"attempted\"}},\"object\":{\"objectType\":\"Activity\",\"id\":\"https://example.com/activity/simplestatement\",\"definition\":{\"name\":{\"en\":\"Simple Statement\"}}},\"attachments\":[{\"usageType\":\"http://adlnet.gov/expapi/attachments/code\",\"display\":{\"en\":\"binary attachment\"},\"contentType\":\"application/octet-stream\",\"length\":6,\"fileUrl\":\"example.com/attachment\"}]}"));
+  }
+
+  @Test
+  void whenPostingSubStatementWithTextAttachmentThenBodyIsExpected() throws InterruptedException {
+
+    mockWebServer.enqueue(new MockResponse().setStatus("HTTP/1.1 200 OK")
+        .setBody("[\"19a74a3f-7354-4254-aa4a-1c39ab4f2ca7\"]")
+        .setHeader("Content-Type", "application/json"));
+
+    // When Posting SubStatement With Text Attachment
+    client.postStatement(r -> r.statement(s -> s
+        .actor(a -> a.name("A N Other").mbox("mailto:another@example.com"))
+
+        .verb(Verb.ABANDONED)
+
+        .object(SubStatement.builder()
+
+            .actor(Agent.builder().name("A N Other").mbox("mailto:another@example.com").build())
+
+            .verb(Verb.ATTENDED)
+
+            .object(Activity.builder().id("https://example.com/activity/simplestatement")
+                .definition(d -> d.addName(Locale.ENGLISH, "Simple Statement")).build())
+
+            .addAttachment(a -> a.content("Simple attachment").length(17).contentType("text/plain")
+                .usageType(URI.create("http://adlnet.gov/expapi/attachments/text"))
+                .addDisplay(Locale.ENGLISH, "text attachment"))
+
+            .build())
+
+    )).block();
+
+    final var recordedRequest = mockWebServer.takeRequest();
+
+    // Then Body Is Expected
+    assertThat(recordedRequest.getBody().readUtf8(), is(
+        "--xapi-learning-dev-boundary\r\nContent-Type:application/json\r\n\r\n{\"actor\":{\"objectType\":\"Agent\",\"name\":\"A N Other\",\"mbox\":\"mailto:another@example.com\"},\"verb\":{\"id\":\"https://w3id.org/xapi/adl/verbs/abandoned\",\"display\":{\"und\":\"abandoned\"}},\"object\":{\"objectType\":\"SubStatement\",\"actor\":{\"objectType\":\"Agent\",\"name\":\"A N Other\",\"mbox\":\"mailto:another@example.com\"},\"verb\":{\"id\":\"http://adlnet.gov/expapi/verbs/attended\",\"display\":{\"und\":\"attended\"}},\"object\":{\"objectType\":\"Activity\",\"id\":\"https://example.com/activity/simplestatement\",\"definition\":{\"name\":{\"en\":\"Simple Statement\"}}},\"attachments\":[{\"usageType\":\"http://adlnet.gov/expapi/attachments/text\",\"display\":{\"en\":\"text attachment\"},\"contentType\":\"text/plain\",\"length\":17,\"sha2\":\"b154d3fd46a5068da42ba05a8b9c971688ab5a57eb5c3a0e50a23c42a86786e5\"}]}}\r\n--xapi-learning-dev-boundary\r\nContent-Type:text/plain\r\nContent-Transfer-Encoding:binary\r\nX-Experience-API-Hash:b154d3fd46a5068da42ba05a8b9c971688ab5a57eb5c3a0e50a23c42a86786e5\r\n\r\nSimple attachment\r\n--xapi-learning-dev-boundary--"));
+  }
+
+  @Test
+  void whenPostingStatementsWithAttachmentsThenBodyIsExpected() throws InterruptedException {
+
+    mockWebServer.enqueue(new MockResponse().setStatus("HTTP/1.1 200 OK")
+        .setBody("[\"19a74a3f-7354-4254-aa4a-1c39ab4f2ca7\"]")
+        .setHeader("Content-Type", "application/json"));
+
+    // When Posting Statements With Attachments
+    final var statement1 = Statement.builder()
+
+        .actor(a -> a.name("A N Other").mbox("mailto:another@example.com"))
+
+        .addAttachment(a -> a.content(new byte[] {64, 65, 66, 67, 68, 69}).length(6)
+            .contentType("application/octet-stream")
+            .usageType(URI.create("http://adlnet.gov/expapi/attachments/code"))
+            .addDisplay(Locale.ENGLISH, "binary attachment"))
+
+        .verb(Verb.ATTEMPTED)
+
+        .activityObject(o -> o.id("https://example.com/activity/simplestatement")
+            .definition(d -> d.addName(Locale.ENGLISH, "Simple Statement")))
+
+        .build();
+
+    final var statement2 = Statement.builder()
+
+        .actor(a -> a.name("A N Other").mbox("mailto:another@example.com"))
+
+        .addAttachment(a -> a.content(new byte[] {64, 65, 66, 67, 68, 69}).length(6)
+            .contentType("application/octet-stream")
+            .usageType(URI.create("http://adlnet.gov/expapi/attachments/code"))
+            .addDisplay(Locale.ENGLISH, "binary attachment"))
+
+        .addAttachment(a -> a.content("Simple attachment").length(17).contentType("text/plain")
+            .usageType(URI.create("http://adlnet.gov/expapi/attachments/text"))
+            .addDisplay(Locale.ENGLISH, "text attachment"))
+
+        .verb(Verb.ATTEMPTED)
+
+        .activityObject(o -> o.id("https://example.com/activity/simplestatement")
+            .definition(d -> d.addName(Locale.ENGLISH, "Simple Statement")))
+
+        .build();
+
+    // When posting Statements
+    client.postStatements(r -> r.statements(statement1, statement2)).block();
+
+    final var recordedRequest = mockWebServer.takeRequest();
+
+    // Then Body Is Expected
+    assertThat(recordedRequest.getBody().readUtf8(), is(
+        "--xapi-learning-dev-boundary\r\nContent-Type:application/json\r\n\r\n[{\"actor\":{\"objectType\":\"Agent\",\"name\":\"A N Other\",\"mbox\":\"mailto:another@example.com\"},\"verb\":{\"id\":\"http://adlnet.gov/expapi/verbs/attempted\",\"display\":{\"und\":\"attempted\"}},\"object\":{\"objectType\":\"Activity\",\"id\":\"https://example.com/activity/simplestatement\",\"definition\":{\"name\":{\"en\":\"Simple Statement\"}}},\"attachments\":[{\"usageType\":\"http://adlnet.gov/expapi/attachments/code\",\"display\":{\"en\":\"binary attachment\"},\"contentType\":\"application/octet-stream\",\"length\":6,\"sha2\":\"0ff3c6749b3eeaae17254fdf0e2de1f32b21c592f474bf39b62b398e8a787eef\"}]},{\"actor\":{\"objectType\":\"Agent\",\"name\":\"A N Other\",\"mbox\":\"mailto:another@example.com\"},\"verb\":{\"id\":\"http://adlnet.gov/expapi/verbs/attempted\",\"display\":{\"und\":\"attempted\"}},\"object\":{\"objectType\":\"Activity\",\"id\":\"https://example.com/activity/simplestatement\",\"definition\":{\"name\":{\"en\":\"Simple Statement\"}}},\"attachments\":[{\"usageType\":\"http://adlnet.gov/expapi/attachments/code\",\"display\":{\"en\":\"binary attachment\"},\"contentType\":\"application/octet-stream\",\"length\":6,\"sha2\":\"0ff3c6749b3eeaae17254fdf0e2de1f32b21c592f474bf39b62b398e8a787eef\"},{\"usageType\":\"http://adlnet.gov/expapi/attachments/text\",\"display\":{\"en\":\"text attachment\"},\"contentType\":\"text/plain\",\"length\":17,\"sha2\":\"b154d3fd46a5068da42ba05a8b9c971688ab5a57eb5c3a0e50a23c42a86786e5\"}]}]\r\n--xapi-learning-dev-boundary\r\nContent-Type:text/plain\r\nContent-Transfer-Encoding:binary\r\nX-Experience-API-Hash:b154d3fd46a5068da42ba05a8b9c971688ab5a57eb5c3a0e50a23c42a86786e5\r\n\r\nSimple attachment\r\n--xapi-learning-dev-boundary\r\nContent-Type:application/octet-stream\r\nContent-Transfer-Encoding:binary\r\nX-Experience-API-Hash:0ff3c6749b3eeaae17254fdf0e2de1f32b21c592f474bf39b62b398e8a787eef\r\n\r\n@ABCDE\r\n--xapi-learning-dev-boundary--"));
+  }
+
+
+
+  @Test
+  void whenPostingStatementsWithTimestampAndAttachmentThenNoExceptionIsThrown()
+      throws InterruptedException {
+
+    mockWebServer.enqueue(new MockResponse().setStatus("HTTP/1.1 200 OK")
+        .setBody("[\"19a74a3f-7354-4254-aa4a-1c39ab4f2ca7\"]")
+        .setHeader("Content-Type", "application/json"));
+
+    final var statement = Statement.builder()
+
+        .actor(a -> a.name("A N Other").mbox("mailto:another@example.com"))
+
+        .verb(Verb.ATTEMPTED)
+
+        .activityObject(o -> o.id("https://example.com/activity/simplestatement"))
+
+        .addAttachment(a -> a.content(new byte[] {64, 65, 66, 67, 68, 69}).length(6)
+            .contentType("application/octet-stream")
+            .usageType(URI.create("http://example.com/attachment"))
+            .addDisplay(Locale.ENGLISH, "binary attachment"))
+
+        .timestamp(Instant.now())
+
+        .build();
+
+    // When Posting Statements With Timestamp And Attachment
+
+    // Then No Exception Is Thrown
+    assertDoesNotThrow(() -> client.postStatements(r -> r.statements(statement)).block());
+
+  }
+
+
+
+}
diff --git a/xapi-client/src/test/java/dev/learning/xapi/client/XapiClientTests.java b/xapi-client/src/test/java/dev/learning/xapi/client/XapiClientTests.java
index 2300b3ee..bce73ac9 100644
--- a/xapi-client/src/test/java/dev/learning/xapi/client/XapiClientTests.java
+++ b/xapi-client/src/test/java/dev/learning/xapi/client/XapiClientTests.java
@@ -7,6 +7,7 @@
 import static org.hamcrest.core.Is.is;
 import static org.hamcrest.core.IsInstanceOf.instanceOf;
 
+import com.fasterxml.jackson.databind.ObjectMapper;
 import dev.learning.xapi.model.About;
 import dev.learning.xapi.model.Activity;
 import dev.learning.xapi.model.Person;
@@ -44,6 +45,9 @@ class XapiClientTests {
   @Autowired
   private WebClient.Builder webClientBuilder;
 
+  @Autowired
+  private ObjectMapper objectMapper;
+
   private MockWebServer mockWebServer;
   private XapiClient client;
 
@@ -54,7 +58,7 @@ void setUp() throws Exception {
 
     webClientBuilder.baseUrl(mockWebServer.url("").toString());
 
-    client = new XapiClient(webClientBuilder);
+    client = new XapiClient(webClientBuilder, objectMapper);
 
   }
 
@@ -104,8 +108,8 @@ void whenGettingStatementThenBodyIsInstanceOfStatement() throws InterruptedExcep
         .addHeader("Content-Type", "application/json; charset=utf-8"));
 
     // When Getting Statement
-    final var response =
-        client.getStatement(r -> r.id("4df42866-40e7-45b6-bf7c-8d5fccbdccd6")).block();
+    final var response = client.getStatement(r -> r.id("4df42866-40e7-45b6-bf7c-8d5fccbdccd6"))
+        .block();
 
     // Then Body Is Instance Of Statement
     assertThat(response.getBody(), instanceOf(Statement.class));
@@ -176,7 +180,6 @@ void whenPostingStatementsThenMethodIsPost() throws InterruptedException {
     assertThat(recordedRequest.getMethod(), is("POST"));
   }
 
-  
   @Test
   void whenPostingStatementsThenBodyIsExpected() throws InterruptedException {
 
@@ -205,7 +208,6 @@ void whenPostingStatementsThenBodyIsExpected() throws InterruptedException {
         "[{\"actor\":{\"objectType\":\"Agent\",\"name\":\"A N Other\",\"mbox\":\"mailto:another@example.com\"},\"verb\":{\"id\":\"http://adlnet.gov/expapi/verbs/attempted\",\"display\":{\"und\":\"attempted\"}},\"object\":{\"objectType\":\"Activity\",\"id\":\"https://example.com/activity/simplestatement\",\"definition\":{\"name\":{\"en\":\"Simple Statement\"}}}},{\"actor\":{\"objectType\":\"Agent\",\"name\":\"A N Other\",\"mbox\":\"mailto:another@example.com\"},\"verb\":{\"id\":\"http://adlnet.gov/expapi/verbs/passed\",\"display\":{\"und\":\"passed\"}},\"object\":{\"objectType\":\"Activity\",\"id\":\"https://example.com/activity/simplestatement\",\"definition\":{\"name\":{\"en\":\"Simple Statement\"}}}}]"));
   }
 
-  
   @Test
   void whenPostingStatementsArrayThenBodyIsExpected() throws InterruptedException {
 
@@ -1798,8 +1800,8 @@ void whenGettingAgentsThenBodyIsInstanceOfPerson() throws InterruptedException {
         .addHeader("Content-Type", "application/json; charset=utf-8"));
 
     // When Getting Agents
-    final var response =
-        client.getAgents(r -> r.agent(a -> a.mbox("mailto:another@example.com"))).block();
+    final var response = client.getAgents(r -> r.agent(a -> a.mbox("mailto:another@example.com")))
+        .block();
 
     // Then Body Is Instance Of Activity
     assertThat(response.getBody(), instanceOf(Person.class));
diff --git a/xapi-client/src/test/java/dev/learning/xapi/client/configuration/XapiClientAutoConfigurationAuthorizationTest.java b/xapi-client/src/test/java/dev/learning/xapi/client/configuration/XapiClientAutoConfigurationAuthorizationTest.java
index b2138ce9..54983f7d 100644
--- a/xapi-client/src/test/java/dev/learning/xapi/client/configuration/XapiClientAutoConfigurationAuthorizationTest.java
+++ b/xapi-client/src/test/java/dev/learning/xapi/client/configuration/XapiClientAutoConfigurationAuthorizationTest.java
@@ -16,6 +16,7 @@
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration;
 import org.springframework.boot.autoconfigure.web.reactive.function.client.WebClientAutoConfiguration;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.http.HttpHeaders;
@@ -29,7 +30,7 @@
 @DisplayName("XapiClientAutoConfigurationAuthorization Test")
 @SpringBootTest(
     classes = { XapiClientAutoConfiguration.class, WebClientAutoConfiguration.class,
-        XapiTestClientConfiguration2.class },
+        XapiTestClientConfiguration2.class, JacksonAutoConfiguration.class },
     properties = "xapi.client.authorization = bearer 1234")
 class XapiClientAutoConfigurationAuthorizationTest {
 
diff --git a/xapi-client/src/test/java/dev/learning/xapi/client/configuration/XapiClientAutoConfigurationBaseUrlTest.java b/xapi-client/src/test/java/dev/learning/xapi/client/configuration/XapiClientAutoConfigurationBaseUrlTest.java
index f8d936c5..503e56ff 100644
--- a/xapi-client/src/test/java/dev/learning/xapi/client/configuration/XapiClientAutoConfigurationBaseUrlTest.java
+++ b/xapi-client/src/test/java/dev/learning/xapi/client/configuration/XapiClientAutoConfigurationBaseUrlTest.java
@@ -4,6 +4,7 @@
 package dev.learning.xapi.client.configuration;
 
 import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.core.AnyOf.anyOf;
 import static org.hamcrest.core.Is.is;
 
 import dev.learning.xapi.client.XapiClient;
@@ -14,6 +15,7 @@
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration;
 import org.springframework.boot.autoconfigure.web.reactive.function.client.WebClientAutoConfiguration;
 import org.springframework.boot.test.context.SpringBootTest;
 
@@ -23,8 +25,10 @@
  * @author István Rátkai (Selindek)
  */
 @DisplayName("XapiClientAutoConfigurationBaseUrl Test")
-@SpringBootTest(classes = {XapiClientAutoConfiguration.class, WebClientAutoConfiguration.class},
-    properties = {"xapi.client.baseUrl = http://127.0.0.1:55123/"})
+@SpringBootTest(
+    classes = { XapiClientAutoConfiguration.class, WebClientAutoConfiguration.class,
+        JacksonAutoConfiguration.class },
+    properties = { "xapi.client.baseUrl = http://127.0.0.1:55123/" })
 class XapiClientAutoConfigurationBaseUrlTest {
 
   @Autowired
@@ -52,8 +56,9 @@ void whenConfiguringXapiClientThenBaseUrlIsSet() throws InterruptedException {
     final var recordedRequest = mockWebServer.takeRequest();
 
     // Then BaseUrl Is Set (Request was sent to the proper url)
-    assertThat(recordedRequest.getRequestUrl().toString(),
-        is("http://localhost:55123/statements?statementId=4df42866-40e7-45b6-bf7c-8d5fccbdccd6"));
+    assertThat(recordedRequest.getRequestUrl().toString(), anyOf(
+        is("http://127.0.0.1:55123/statements?statementId=4df42866-40e7-45b6-bf7c-8d5fccbdccd6"),
+        is("http://localhost:55123/statements?statementId=4df42866-40e7-45b6-bf7c-8d5fccbdccd6")));
   }
 
 }
diff --git a/xapi-client/src/test/java/dev/learning/xapi/client/configuration/XapiClientAutoConfigurationUsernamePasswordTest.java b/xapi-client/src/test/java/dev/learning/xapi/client/configuration/XapiClientAutoConfigurationUsernamePasswordTest.java
index afcdd7e5..e1fa55ff 100644
--- a/xapi-client/src/test/java/dev/learning/xapi/client/configuration/XapiClientAutoConfigurationUsernamePasswordTest.java
+++ b/xapi-client/src/test/java/dev/learning/xapi/client/configuration/XapiClientAutoConfigurationUsernamePasswordTest.java
@@ -16,6 +16,7 @@
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration;
 import org.springframework.boot.autoconfigure.web.reactive.function.client.WebClientAutoConfiguration;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.http.HttpHeaders;
@@ -29,7 +30,7 @@
 @DisplayName("XapiClientAutoConfigurationUsernamePassword Test")
 @SpringBootTest(
     classes = { XapiClientAutoConfiguration.class, WebClientAutoConfiguration.class,
-        XapiTestClientConfiguration.class },
+        XapiTestClientConfiguration.class, JacksonAutoConfiguration.class },
     properties = { "xapi.client.username = username", "xapi.client.password = password" })
 class XapiClientAutoConfigurationUsernamePasswordTest {
 
diff --git a/xapi-model/src/main/java/dev/learning/xapi/model/Attachment.java b/xapi-model/src/main/java/dev/learning/xapi/model/Attachment.java
index 48dfb75b..45b7dfb9 100644
--- a/xapi-model/src/main/java/dev/learning/xapi/model/Attachment.java
+++ b/xapi-model/src/main/java/dev/learning/xapi/model/Attachment.java
@@ -4,10 +4,14 @@
 
 package dev.learning.xapi.model;
 
+import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.annotation.JsonInclude.Include;
 import jakarta.validation.constraints.NotNull;
 import java.net.URI;
+import java.nio.charset.StandardCharsets;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
 import java.util.Locale;
 import lombok.Builder;
 import lombok.Value;
@@ -69,6 +73,12 @@ public class Attachment {
    */
   private URI fileUrl;
 
+  /**
+   * The data of the attachment as byte array.
+   */
+  @JsonIgnore
+  private byte[] content;
+
   // **Warning** do not add fields that are not required by the xAPI specification.
 
   /**
@@ -117,6 +127,93 @@ public Builder addDescription(Locale key, String value) {
       return this;
 
     }
+
+    /**
+     * <p>
+     * Sets SHA-2 hash of the Attachment.
+     * </p>
+     * <p>
+     * The sha2 is set ONLY if the content property was not set yet. (otherwise the sha2 is
+     * calculated automatically)
+     * </p>
+     *
+     * @param sha2 The SHA-2 hash of the Attachment data.
+     *
+     * @return This builder
+     */
+    public Builder sha2(String sha2) {
+      if (this.content == null) {
+        this.sha2 = sha2;
+      }
+
+      return this;
+
+    }
+
+    /**
+     * <p>
+     * Sets data of the Attachment.
+     * </p>
+     * <p>
+     * This method also automatically calculates the SHA-2 hash for the data.
+     * </p>
+     *
+     * @param content The data of the Attachment as a byte array.
+     *
+     * @return This builder
+     */
+    public Builder content(byte[] content) {
+      this.content = content;
+      if (content != null) {
+        this.sha2 = sha256Hex(content);
+      }
+
+      return this;
+
+    }
+
+    /**
+     * <p>
+     * Sets data of the Attachment as a String.
+     * </p>
+     * <p>
+     * This is a convenient method for creating text attachments.
+     * </p>
+     *
+     * @param content The data of the Attachment as a String.
+     *
+     * @return This builder
+     *
+     * @see Builder#content(byte[])
+     */
+    public Builder content(String content) {
+
+      if (content != null) {
+        return content(content.getBytes(StandardCharsets.UTF_8));
+      }
+
+      return content((byte[]) null);
+
+    }
+
+    private static String sha256Hex(byte[] data) {
+      try {
+        final var digest = MessageDigest.getInstance("SHA-256");
+        final var hash = digest.digest(data);
+        final var hexString = new StringBuilder(2 * hash.length);
+        for (final byte element : hash) {
+          final var hex = Integer.toHexString(0xff & element);
+          if (hex.length() == 1) {
+            hexString.append('0');
+          }
+          hexString.append(hex);
+        }
+        return hexString.toString();
+      } catch (final NoSuchAlgorithmException e) {
+        throw new IllegalArgumentException(e);
+      }
+
+    }
   }
 
 }
diff --git a/xapi-model/src/main/java/dev/learning/xapi/model/Statement.java b/xapi-model/src/main/java/dev/learning/xapi/model/Statement.java
index 65775162..3c94b89c 100644
--- a/xapi-model/src/main/java/dev/learning/xapi/model/Statement.java
+++ b/xapi-model/src/main/java/dev/learning/xapi/model/Statement.java
@@ -17,6 +17,7 @@
 import jakarta.validation.constraints.NotNull;
 import jakarta.validation.constraints.Pattern;
 import java.time.Instant;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.UUID;
 import java.util.function.Consumer;
@@ -318,6 +319,42 @@ public Builder context(Context context) {
       return this;
     }
 
+    /**
+     * Adds an attachment.
+     *
+     * @param attachment An {@link Attachment} object.
+     *
+     * @return This builder
+     * 
+     * @see Statement#attachments
+     */
+    public Builder addAttachment(Attachment attachment) {
+
+      if (this.attachments == null) {
+        this.attachments = new ArrayList<>();
+      }
+
+      this.attachments.add(attachment);
+      return this;
+    }
+    
+    /**
+     * Consumer Builder for attachment.
+     *
+     * @param attachment The Consumer Builder for attachment
+     *
+     * @return This builder
+     *
+     * @see Statement#attachments
+     */
+    public Builder addAttachment(Consumer<Attachment.Builder> attachment) {
+
+      final Attachment.Builder builder = Attachment.builder();
+
+      attachment.accept(builder);
+
+      return addAttachment(builder.build());
+    }
   }
 
 }
diff --git a/xapi-model/src/main/java/dev/learning/xapi/model/SubStatement.java b/xapi-model/src/main/java/dev/learning/xapi/model/SubStatement.java
index 98fae6ec..0f3c8b13 100644
--- a/xapi-model/src/main/java/dev/learning/xapi/model/SubStatement.java
+++ b/xapi-model/src/main/java/dev/learning/xapi/model/SubStatement.java
@@ -10,6 +10,7 @@
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.NotNull;
 import java.time.Instant;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.function.Consumer;
 import lombok.Builder;
@@ -159,6 +160,42 @@ public Builder verb(Verb verb) {
       return this;
     }
 
+    /**
+     * Consumer Builder for attachment.
+     *
+     * @param attachment The Consumer Builder for attachment
+     *
+     * @return This builder
+     *
+     * @see SubStatement#attachments
+     */
+    public Builder addAttachment(Consumer<Attachment.Builder> attachment) {
+
+      final Attachment.Builder builder = Attachment.builder();
+
+      attachment.accept(builder);
+
+      return addAttachment(builder.build());
+    }    
+    
+    /**
+     * Adds an attachment.
+     *
+     * @param attachment An {@link Attachment} object.
+     *
+     * @return This builder
+     * 
+     * @see SubStatement#attachments
+     */
+    public Builder addAttachment(Attachment attachment) {
+
+      if (this.attachments == null) {
+        this.attachments = new ArrayList<>();
+      }
+
+      this.attachments.add(attachment);
+      return this;
+    }
   }
 
 }
diff --git a/xapi-model/src/test/java/dev/learning/xapi/model/AttachmentTests.java b/xapi-model/src/test/java/dev/learning/xapi/model/AttachmentTests.java
index cf464b1c..88825e6e 100644
--- a/xapi-model/src/test/java/dev/learning/xapi/model/AttachmentTests.java
+++ b/xapi-model/src/test/java/dev/learning/xapi/model/AttachmentTests.java
@@ -9,15 +9,17 @@
 import static org.hamcrest.Matchers.hasSize;
 import static org.hamcrest.Matchers.instanceOf;
 import static org.hamcrest.Matchers.is;
+import static org.junit.jupiter.api.Assertions.assertNull;
 
-import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import jakarta.validation.ConstraintViolation;
 import jakarta.validation.Validation;
 import jakarta.validation.Validator;
-import java.io.File;
+import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.net.URI;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
 import java.util.Locale;
 import java.util.Set;
 import org.junit.jupiter.api.DisplayName;
@@ -29,6 +31,8 @@
  *
  * @author Lukáš Sahula
  * @author Martin Myslik
+ * @author Thomas Turrell-Croft
+ * @author István Rátkai (Selindek)
  */
 @DisplayName("Attachment tests")
 class AttachmentTests {
@@ -38,12 +42,12 @@ class AttachmentTests {
   private final Validator validator = Validation.buildDefaultValidatorFactory().getValidator();
 
   @Test
-  void whenDeserializingActivityDefinitionThenResultIsInstanceOfAttachment() throws Exception {
+  void whenDeserializingAttachmentThenResultIsInstanceOfAttachment() throws Exception {
 
-    final File file = ResourceUtils.getFile("classpath:attachment/attachment.json");
+    final var file = ResourceUtils.getFile("classpath:attachment/attachment.json");
 
-    // When Deserializing ActivityDefinition
-    final Attachment result = objectMapper.readValue(file, Attachment.class);
+    // When Deserializing Attachment
+    final var result = objectMapper.readValue(file, Attachment.class);
 
     // Then Result Is Instance Of Attachment
     assertThat(result, instanceOf(Attachment.class));
@@ -51,12 +55,12 @@ void whenDeserializingActivityDefinitionThenResultIsInstanceOfAttachment() throw
   }
 
   @Test
-  void whenDeserializingActivityDefinitionThenUsageTypeIsExpected() throws Exception {
+  void whenDeserializingAttachmentThenUsageTypeIsExpected() throws Exception {
 
-    final File file = ResourceUtils.getFile("classpath:attachment/attachment.json");
+    final var file = ResourceUtils.getFile("classpath:attachment/attachment.json");
 
-    // When Deserializing ActivityDefinition
-    final Attachment result = objectMapper.readValue(file, Attachment.class);
+    // When Deserializing Attachment
+    final var result = objectMapper.readValue(file, Attachment.class);
 
     // Then UsageType Is Expected
     assertThat(result.getUsageType(),
@@ -65,12 +69,12 @@ void whenDeserializingActivityDefinitionThenUsageTypeIsExpected() throws Excepti
   }
 
   @Test
-  void whenDeserializingActivityDefinitionThenDisplayIsExpected() throws Exception {
+  void whenDeserializingAttachmentThenDisplayIsExpected() throws Exception {
 
-    final File file = ResourceUtils.getFile("classpath:attachment/attachment.json");
+    final var file = ResourceUtils.getFile("classpath:attachment/attachment.json");
 
-    // When Deserializing ActivityDefinition
-    final Attachment result = objectMapper.readValue(file, Attachment.class);
+    // When Deserializing Attachment
+    final var result = objectMapper.readValue(file, Attachment.class);
 
     // Then Display Is Expected
     assertThat(result.getDisplay().get(Locale.US), is("Signature"));
@@ -78,12 +82,12 @@ void whenDeserializingActivityDefinitionThenDisplayIsExpected() throws Exception
   }
 
   @Test
-  void whenDeserializingActivityDefinitionThenDescriptionIsExpected() throws Exception {
+  void whenDeserializingAttachmentThenDescriptionIsExpected() throws Exception {
 
-    final File file = ResourceUtils.getFile("classpath:attachment/attachment.json");
+    final var file = ResourceUtils.getFile("classpath:attachment/attachment.json");
 
-    // When Deserializing ActivityDefinition
-    final Attachment result = objectMapper.readValue(file, Attachment.class);
+    // When Deserializing Attachment
+    final var result = objectMapper.readValue(file, Attachment.class);
 
     // Then Description Is Expected
     assertThat(result.getDescription().get(Locale.US), is("A test signature"));
@@ -91,12 +95,12 @@ void whenDeserializingActivityDefinitionThenDescriptionIsExpected() throws Excep
   }
 
   @Test
-  void whenDeserializingActivityDefinitionThenContentTypeIsExpected() throws Exception {
+  void whenDeserializingAttachmentThenContentTypeIsExpected() throws Exception {
 
-    final File file = ResourceUtils.getFile("classpath:attachment/attachment.json");
+    final var file = ResourceUtils.getFile("classpath:attachment/attachment.json");
 
-    // When Deserializing ActivityDefinition
-    final Attachment result = objectMapper.readValue(file, Attachment.class);
+    // When Deserializing Attachment
+    final var result = objectMapper.readValue(file, Attachment.class);
 
     // Then ContentType Is Expected
     assertThat(result.getContentType(), is("application/octet-stream"));
@@ -104,12 +108,12 @@ void whenDeserializingActivityDefinitionThenContentTypeIsExpected() throws Excep
   }
 
   @Test
-  void whenDeserializingActivityDefinitionThenLengthIsExpected() throws Exception {
+  void whenDeserializingAttachmentThenLengthIsExpected() throws Exception {
 
-    final File file = ResourceUtils.getFile("classpath:attachment/attachment.json");
+    final var file = ResourceUtils.getFile("classpath:attachment/attachment.json");
 
-    // When Deserializing ActivityDefinition
-    final Attachment result = objectMapper.readValue(file, Attachment.class);
+    // When Deserializing Attachment
+    final var result = objectMapper.readValue(file, Attachment.class);
 
     // Then Length Is Expected
     assertThat(result.getLength(), is(4235));
@@ -117,12 +121,12 @@ void whenDeserializingActivityDefinitionThenLengthIsExpected() throws Exception
   }
 
   @Test
-  void whenDeserializingActivityDefinitionThenSha2IsExpected() throws Exception {
+  void whenDeserializingAttachmentThenSha2IsExpected() throws Exception {
 
-    final File file = ResourceUtils.getFile("classpath:attachment/attachment.json");
+    final var file = ResourceUtils.getFile("classpath:attachment/attachment.json");
 
-    // When Deserializing ActivityDefinition
-    final Attachment result = objectMapper.readValue(file, Attachment.class);
+    // When Deserializing Attachment
+    final var result = objectMapper.readValue(file, Attachment.class);
 
     // Then Sha2 Is Expected
     assertThat(result.getSha2(),
@@ -131,12 +135,12 @@ void whenDeserializingActivityDefinitionThenSha2IsExpected() throws Exception {
   }
 
   @Test
-  void whenDeserializingActivityDefinitionThenFileUrlIsExpected() throws Exception {
+  void whenDeserializingAttachmentThenFileUrlIsExpected() throws Exception {
 
-    final File file = ResourceUtils.getFile("classpath:attachment/attachment.json");
+    final var file = ResourceUtils.getFile("classpath:attachment/attachment.json");
 
-    // When Deserializing ActivityDefinition
-    final Attachment result = objectMapper.readValue(file, Attachment.class);
+    // When Deserializing Attachment
+    final var result = objectMapper.readValue(file, Attachment.class);
 
     // Then FileUrl Is Expected
     assertThat(result.getFileUrl(), is(URI.create("https://example.com")));
@@ -146,7 +150,7 @@ void whenDeserializingActivityDefinitionThenFileUrlIsExpected() throws Exception
   @Test
   void whenSerializingAttachmentThenResultIsEqualToExpectedJson() throws IOException {
 
-    final Attachment attachment = Attachment.builder()
+    final var attachment = Attachment.builder()
 
         .usageType(URI.create("http://adlnet.gov/expapi/attachments/signature"))
 
@@ -165,7 +169,7 @@ void whenSerializingAttachmentThenResultIsEqualToExpectedJson() throws IOExcepti
         .build();
 
     // When Serializing Attachment
-    final JsonNode result = objectMapper.readTree(objectMapper.writeValueAsString(attachment));
+    final var result = objectMapper.readTree(objectMapper.writeValueAsString(attachment));
 
     // Then Result Is Equal To Expected Json
     assertThat(result,
@@ -177,15 +181,15 @@ void whenSerializingAttachmentThenResultIsEqualToExpectedJson() throws IOExcepti
   @Test
   void whenCallingToStringThenResultIsExpected() throws IOException {
 
-    final Attachment attachment = objectMapper
+    final var attachment = objectMapper
         .readValue(ResourceUtils.getFile("classpath:attachment/attachment.json"), Attachment.class);
 
     // When Calling ToString
-    final String result = attachment.toString();
+    final var result = attachment.toString();
 
     // Then Result Is Expected
     assertThat(result, is(
-        "Attachment(usageType=http://adlnet.gov/expapi/attachments/signature, display={en_US=Signature}, description={en_US=A test signature}, contentType=application/octet-stream, length=4235, sha2=672fa5fa658017f1b72d65036f13379c6ab05d4ab3b6664908d8acf0b6a0c634, fileUrl=https://example.com)"));
+        "Attachment(usageType=http://adlnet.gov/expapi/attachments/signature, display={en_US=Signature}, description={en_US=A test signature}, contentType=application/octet-stream, length=4235, sha2=672fa5fa658017f1b72d65036f13379c6ab05d4ab3b6664908d8acf0b6a0c634, fileUrl=https://example.com, content=null)"));
 
   }
 
@@ -193,11 +197,166 @@ void whenCallingToStringThenResultIsExpected() throws IOException {
    * Builder Tests
    */
 
+  @Test
+  void whenBuildingAttachmentWithDataThenDataIsSet() {
+
+    // When Building Attachment With Data
+    final var attachment = Attachment.builder()
+
+        .usageType(URI.create("http://adlnet.gov/expapi/attachments/text"))
+
+        .addDisplay(Locale.US, "Text")
+
+        .contentType("plain/text")
+
+        .length(4)
+
+        .content("text")
+
+        .fileUrl(URI.create("https://example.com"))
+
+        .build();
+
+    // Then Data Is Set
+    assertThat(new String(attachment.getContent(), StandardCharsets.UTF_8), is("text"));
+
+  }
+
+  @Test
+  void givenAttachmentWithStringDataWhenGettingSHA2ThenResultIsExpected() {
+
+    // Given Attachment With String Data
+    final var attachment = Attachment.builder()
+
+        .content("Simple attachment").length(17)
+
+        .contentType("text/plain")
+
+        .usageType(URI.create("https://example.com/attachments/greeting"))
+
+        .addDisplay(Locale.ENGLISH, "text attachment")
+
+        .build();
+
+    // When Getting SHA2
+    final var result = attachment.getSha2();
+
+    // Then Result Is Expected
+    assertThat(result, is("b154d3fd46a5068da42ba05a8b9c971688ab5a57eb5c3a0e50a23c42a86786e5"));
+
+  }
+
+  @Test
+  void givenAttachmentWithBinaryDataWhenGettingSHA2ThenResultIsExpected()
+      throws FileNotFoundException, IOException {
+
+    final var data =
+        Files.readAllBytes(ResourceUtils.getFile("classpath:attachment/example.jpg").toPath());
+
+    // Given Attachment With Binary Data
+    final var attachment = Attachment.builder()
+
+        .content(data).length(data.length)
+
+        .contentType("image/jpeg")
+
+        .usageType(URI.create("https://example.com/attachments/greeting"))
+
+        .addDisplay(Locale.ENGLISH, "JPEG attachment")
+
+        .build();
+
+    // When Getting SHA2
+    final var result = attachment.getSha2();
+
+    // Then Result Is Expected
+    assertThat(result, is("27c7a7c1e3d2ff43e4ee1a8915fef351d1ef75d5aeff873e9b2893f4589dcdcc"));
+
+  }
+
+  @Test
+  void whenBuildingAttachmentWithDataAndSha2ThenSha2IsTheCalculatedOne() {
+
+    // When Building Attachment With Data And Sha2
+    final var attachment = Attachment.builder()
+
+        .usageType(URI.create("http://adlnet.gov/expapi/attachments/text"))
+
+        .addDisplay(Locale.US, "Text")
+
+        .contentType("plain/text")
+
+        .length(4)
+
+        .content("text")
+
+        .sha2("000000000000000000000000000000000000000000000")
+
+        .fileUrl(URI.create("https://example.com"))
+
+        .build();
+
+    // Then Sha2 Is Set Is The Calculated One
+    assertThat(attachment.getSha2(),
+        is("982d9e3eb996f559e633f4d194def3761d909f5a3b647d1a851fead67c32c9d1"));
+
+  }
+
+  @Test
+  void whenBuildingAttachmentWithNullByteArrayContentThenSha2IsNull() {
+
+    // When Building Attachment With Null Byte Array Content
+    final var attachment = Attachment.builder()
+
+        .usageType(URI.create("http://adlnet.gov/expapi/attachments/text"))
+
+        .addDisplay(Locale.US, "Text")
+
+        .contentType("plain/text")
+
+        .length(4)
+
+        .content((byte[]) null)
+
+        .fileUrl(URI.create("https://example.com"))
+
+        .build();
+
+    // Then Sha2 Is Null
+    assertNull(attachment.getSha2());
+
+  }
+
+  @Test
+  void whenBuildingAttachmentWithNullStringContentThenSha2IsNull() {
+
+    // When Building Attachment With Null String Content
+    final var attachment = Attachment.builder()
+
+        .usageType(URI.create("http://adlnet.gov/expapi/attachments/text"))
+
+        .addDisplay(Locale.US, "Text")
+
+        .contentType("plain/text")
+
+        .length(4)
+
+        .content((String) null)
+
+        .fileUrl(URI.create("https://example.com"))
+
+        .build();
+
+    // Then Sha2 Is Null
+    assertNull(attachment.getSha2());
+
+  }
+
   @Test
   void whenBuildingAttachmentWithTwoDisplayValuesThenDisplayLanguageMapHasTwoEntries() {
 
     // When Building Attachment With Two Display Values
-    final Attachment attachment = Attachment.builder()
+    final var attachment = Attachment.builder()
 
         .usageType(URI.create("http://adlnet.gov/expapi/attachments/signature"))
 
@@ -226,7 +385,7 @@ void whenBuildingAttachmentWithTwoDisplayValuesThenDisplayLanguageMapHasTwoEntri
   void whenBuildingAttachmentWithTwoDescriptionValuesThenDisplayLanguageMapHasTwoEntries() {
 
     // When Building Attachment With Two Description Values
-    final Attachment attachment = Attachment.builder()
+    final var attachment = Attachment.builder()
 
         .usageType(URI.create("http://adlnet.gov/expapi/attachments/signature"))
 
@@ -254,8 +413,7 @@ void whenBuildingAttachmentWithTwoDescriptionValuesThenDisplayLanguageMapHasTwoE
   @Test
   void whenValidatingAttachmentWithAllRequiredPropertiesThenConstraintViolationsSizeIsZero() {
 
-
-    final Attachment attachment = Attachment.builder()
+    final var attachment = Attachment.builder()
 
         .usageType(URI.create("http://adlnet.gov/expapi/attachments/signature"))
 
@@ -285,7 +443,7 @@ void whenValidatingAttachmentWithAllRequiredPropertiesThenConstraintViolationsSi
   @Test
   void whenValidatingAttachmentWithoutUsageTypeThenConstraintViolationsSizeIsOne() {
 
-    final Attachment attachment = Attachment.builder()
+    final var attachment = Attachment.builder()
 
         .addDisplay(Locale.US, "Signature")
 
@@ -314,7 +472,7 @@ void whenValidatingAttachmentWithoutUsageTypeThenConstraintViolationsSizeIsOne()
   void whenValidatingAttachmentWithoutDisplayThenConstraintViolationsSizeIsOne() {
 
 
-    final Attachment attachment = Attachment.builder()
+    final var attachment = Attachment.builder()
 
         .usageType(URI.create("http://adlnet.gov/expapi/attachments/signature"))
 
@@ -342,7 +500,7 @@ void whenValidatingAttachmentWithoutDisplayThenConstraintViolationsSizeIsOne() {
   @Test
   void whenValidatingAttachmentWithoutContentTypeThenConstraintViolationsSizeIsOne() {
 
-    final Attachment attachment = Attachment.builder()
+    final var attachment = Attachment.builder()
 
         .usageType(URI.create("http://adlnet.gov/expapi/attachments/signature"))
 
@@ -370,7 +528,7 @@ void whenValidatingAttachmentWithoutContentTypeThenConstraintViolationsSizeIsOne
   @Test
   void whenValidatingAttachmentWithoutSha2ThenConstraintViolationsSizeIsOne() {
 
-    final Attachment attachment = Attachment.builder()
+    final var attachment = Attachment.builder()
 
         .usageType(URI.create("http://adlnet.gov/expapi/attachments/signature"))
 
@@ -398,7 +556,7 @@ void whenValidatingAttachmentWithoutSha2ThenConstraintViolationsSizeIsOne() {
   @Test
   void whenValidatingAttachmentWithoutLengthThenConstraintViolationsSizeIsOne() {
 
-    final Attachment attachment = Attachment.builder()
+    final var attachment = Attachment.builder()
 
         .usageType(URI.create("http://adlnet.gov/expapi/attachments/signature"))
 
diff --git a/xapi-model/src/test/java/dev/learning/xapi/model/StatementTests.java b/xapi-model/src/test/java/dev/learning/xapi/model/StatementTests.java
index 52bf14b8..bff16ef0 100644
--- a/xapi-model/src/test/java/dev/learning/xapi/model/StatementTests.java
+++ b/xapi-model/src/test/java/dev/learning/xapi/model/StatementTests.java
@@ -577,5 +577,109 @@ void whenValidatingStatementWithSubStatementWithStatementReferenceThenConstraint
 
   }
 
+  @Test
+  void whenBuildingStatementWithTwoAttachmentsThenAttachmentsHasTwoEntries() {
+    
+    // When Building Statement With Two Attachments
+    final LinkedHashMap<URI, Object> extensions = new LinkedHashMap<>();
+    extensions.put(URI.create("http://name"), "Kilby");
+
+    final Attachment attachment = Attachment.builder().usageType(URI.create("http://example.com"))
+        .fileUrl(URI.create("http://example.com"))
+
+        .addDisplay(Locale.ENGLISH, "value")
+
+        .addDescription(Locale.ENGLISH, "value")
+
+        .length(123)
+
+        .sha2("123")
+
+        .contentType("file")
+
+        .build();
+
+    final Account account = Account.builder()
+
+        .homePage(URI.create("https://example.com"))
+
+        .name("13936749")
+
+        .build();
+
+
+    final Statement statement = Statement.builder()
+
+        .id(UUID.fromString("4b9175ba-367d-4b93-990b-34d4180039f1"))
+
+        .actor(a -> a.name("A N Other"))
+
+        .verb(v -> v.id(URI.create("http://example.com/xapi/verbs#sent-a-statement"))
+            .addDisplay(Locale.US, "attended"))
+
+        .result(r -> r.success(true).completion(true).response("Response").duration("P1D"))
+
+        .context(c -> c
+
+            .registration(UUID.fromString("ec531277-b57b-4c15-8d91-d292c5b2b8f7"))
+
+            .agentInstructor(a -> a.name("A N Other").account(account))
+
+            .team(t -> t.name("Team").mbox("mailto:team@example.com"))
+
+            .platform("Example virtual meeting software")
+
+            .language(Locale.ENGLISH)
+
+            .statementReference(s -> s.id(UUID.fromString("6690e6c9-3ef0-4ed3-8b37-7f3964730bee")))
+
+        )
+
+        .timestamp(Instant.parse("2013-05-18T05:32:34.804+00:00"))
+
+        .stored(Instant.parse("2013-05-18T05:32:34.804+00:00"))
+
+        .agentAuthority(a -> a.account(account))
+
+        .activityObject(a -> a.id("http://www.example.com/meetings/occurances/34534")
+
+            .definition(d -> d.addName(Locale.UK,
+                "A simple Experience API statement. Note that the LRS does not need to have any prior information about the Actor (learner), the verb, or the Activity/object.")
+
+                .addDescription(Locale.UK,
+                    "A simple Experience API statement. Note that the LRS does not need to have any prior information about the Actor (learner), the verb, or the Activity/object.")
+
+                .type(URI.create("http://adlnet.gov/expapi/activities/meeting"))
+
+                .moreInfo(URI.create("http://virtualmeeting.example.com/345256"))
+
+                .extensions(extensions)))
+
+        .addAttachment(attachment)
+
+        .addAttachment(a-> a.usageType(URI.create("http://example.com"))
+            
+            .fileUrl(URI.create("http://example.com/2"))
+
+            .addDisplay(Locale.ENGLISH, "value2")
+
+            .addDescription(Locale.ENGLISH, "value2")
+
+            .length(1234)
+
+            .sha2("1234")
+
+            .contentType("file")
+
+        )
+        
+        .version("1.0.0")
+
+        .build();
+    
+    // Then Attachments Has Two Entries
+    assertThat(statement.getAttachments(), hasSize(2));
+
+  }
 
 }
diff --git a/xapi-model/src/test/java/dev/learning/xapi/model/SubStatementTests.java b/xapi-model/src/test/java/dev/learning/xapi/model/SubStatementTests.java
index da8eb198..c5e8c560 100644
--- a/xapi-model/src/test/java/dev/learning/xapi/model/SubStatementTests.java
+++ b/xapi-model/src/test/java/dev/learning/xapi/model/SubStatementTests.java
@@ -325,7 +325,21 @@ void whenSerializingSubStatementThenResultIsEqualToExpectedJson() throws IOExcep
 
         .context(context)
 
-        .attachments(Collections.singletonList(attachment))
+        .addAttachment(attachment)
+        
+        .addAttachment(a->a.usageType(URI.create("http://example.com"))
+            
+            .fileUrl(URI.create("http://example.com"))
+
+            .addDisplay(Locale.ENGLISH, "value")
+
+            .addDescription(Locale.ENGLISH, "value")
+
+            .length(123)
+
+            .sha2("123")
+
+            .contentType("file"))
 
         .build();
 
@@ -352,7 +366,7 @@ void whenCallingToStringThenResultIsExpected() throws IOException {
 
     // Then Result Is Expected
     assertThat(result, is(
-        "SubStatement(actor=Agent(super=Actor(name=null, mbox=mailto:agent@example.com, mboxSha1sum=null, openid=null, account=null)), verb=Verb(id=http://example.com/confirmed, display={en_US=confirmed}), object=StatementReference(id=9e13cefd-53d3-4eac-b5ed-2cf6693903bb), result=Result(score=Score(scaled=1.0, raw=1.0, min=0.0, max=5.0), success=true, completion=true, response=test, duration=P1D, extensions=null), context=Context(registration=6d969975-8d7e-4506-ac19-877c57f2921a, instructor=Agent(super=Actor(name=null, mbox=mailto:agent@example.com, mboxSha1sum=null, openid=null, account=null)), team=Group(super=Actor(name=Example Group, mbox=null, mboxSha1sum=null, openid=null, account=null), member=null), contextActivities=ContextActivities(parent=[Activity(id=http://www.example.co.uk/exampleactivity, definition=null)], grouping=[Activity(id=http://www.example.co.uk/exampleactivity, definition=null)], category=[Activity(id=http://www.example.co.uk/exampleactivity, definition=null)], other=[Activity(id=http://www.example.co.uk/exampleactivity, definition=null)]), revision=revision, platform=platform, language=en_US, statement=StatementReference(id=9e13cefd-53d3-4eac-b5ed-2cf6693903bb), extensions={http://url=www.example.com}), timestamp=2015-11-18T11:17:00Z, attachments=[Attachment(usageType=http://example.com, display={en_US=value}, description={en_US=value}, contentType=file, length=123, sha2=123, fileUrl=http://example.com)])"));
+        "SubStatement(actor=Agent(super=Actor(name=null, mbox=mailto:agent@example.com, mboxSha1sum=null, openid=null, account=null)), verb=Verb(id=http://example.com/confirmed, display={en_US=confirmed}), object=StatementReference(id=9e13cefd-53d3-4eac-b5ed-2cf6693903bb), result=Result(score=Score(scaled=1.0, raw=1.0, min=0.0, max=5.0), success=true, completion=true, response=test, duration=P1D, extensions=null), context=Context(registration=6d969975-8d7e-4506-ac19-877c57f2921a, instructor=Agent(super=Actor(name=null, mbox=mailto:agent@example.com, mboxSha1sum=null, openid=null, account=null)), team=Group(super=Actor(name=Example Group, mbox=null, mboxSha1sum=null, openid=null, account=null), member=null), contextActivities=ContextActivities(parent=[Activity(id=http://www.example.co.uk/exampleactivity, definition=null)], grouping=[Activity(id=http://www.example.co.uk/exampleactivity, definition=null)], category=[Activity(id=http://www.example.co.uk/exampleactivity, definition=null)], other=[Activity(id=http://www.example.co.uk/exampleactivity, definition=null)]), revision=revision, platform=platform, language=en_US, statement=StatementReference(id=9e13cefd-53d3-4eac-b5ed-2cf6693903bb), extensions={http://url=www.example.com}), timestamp=2015-11-18T11:17:00Z, attachments=[Attachment(usageType=http://example.com, display={en_US=value}, description={en_US=value}, contentType=file, length=123, sha2=123, fileUrl=http://example.com, content=null), Attachment(usageType=http://example.com, display={en=value}, description={en=value}, contentType=file, length=123, sha2=123, fileUrl=http://example.com, content=null)])"));
 
   }
 
diff --git a/xapi-model/src/test/resources/attachment/example.jpg b/xapi-model/src/test/resources/attachment/example.jpg
new file mode 100644
index 00000000..82123354
Binary files /dev/null and b/xapi-model/src/test/resources/attachment/example.jpg differ
diff --git a/xapi-model/src/test/resources/sub_statement/sub_statement.json b/xapi-model/src/test/resources/sub_statement/sub_statement.json
index a4db3e02..234e4dda 100644
--- a/xapi-model/src/test/resources/sub_statement/sub_statement.json
+++ b/xapi-model/src/test/resources/sub_statement/sub_statement.json
@@ -78,5 +78,18 @@
     "length" : 123,
     "sha2" : "123",
     "fileUrl" : "http://example.com"
+  },
+  {
+    "usageType" : "http://example.com",
+    "display" : {
+      "en" : "value"
+    },
+    "description" : {
+      "en" : "value"
+    },
+    "contentType" : "file",
+    "length" : 123,
+    "sha2" : "123",
+    "fileUrl" : "http://example.com"
   } ]
 }