diff --git a/R/str_sentence_case.R b/R/str_sentence_case.R
index 6e5fed1..16d344a 100644
--- a/R/str_sentence_case.R
+++ b/R/str_sentence_case.R
@@ -8,5 +8,10 @@
 #' 
 #' @export
 
-str_sentence_case <- function( string ) 
-  stop( "Sentence case is not implemented yet.")
\ No newline at end of file
+str_sentence_case <- function( string ) {
+    # adapted from https://stackoverflow.com/questions/18509527/first-letter-to-upper-case
+    # behave as expected, even for short string (i.e. "" or "a")
+    substr(string, 1, 1) <- toupper(substr(string, 1, 1))
+    substr(string, 2, nchar(string)) <- tolower(substr(string, 2, nchar(string)))
+    string
+}