diff --git a/README.md b/README.md
index 591277b..e61879d 100644
--- a/README.md
+++ b/README.md
@@ -40,11 +40,17 @@ You can add and remove any number of users at the same time.
 $ gh-auth add chrishunt zachmargolis
 Adding 4 key(s) to '/Users/chris/.ssh/authorized_keys'
 
+$ gh-auth list
+Added users: chrishunt, zachmargolis
+
 $ gh-auth remove chrishunt
 Removing 2 key(s) from '/Users/chris/.ssh/authorized_keys'
 
 $ gh-auth remove zachmargolis
 Removing 2 key(s) from '/Users/chris/.ssh/authorized_keys'
+
+$ gh-auth list
+Added users:
 ```
 
 ## Sections
@@ -72,7 +78,7 @@ Removing 2 key(s) from '/Users/chris/.ssh/authorized_keys'
 `gh-auth` can be used from the command line after the gem has been installed.
 
 ```bash
-usage: gh-auth [--version] [add|remove] <username>
+usage: gh-auth [--version] [add|remove|list] <username>
 ```
 
 ### In Your Project
@@ -102,7 +108,7 @@ Install the `github-auth` gem:
 $ gem install github-auth
 
 $ gh-auth
-usage: gh-auth [--version] [add|remove] <username>
+usage: gh-auth [--version] [add|remove|list] <username>
 ```
 
 ### SSH Public Key Authentication (Mac OS X)
diff --git a/lib/github/auth/cli.rb b/lib/github/auth/cli.rb
index ee54cbd..81a486a 100644
--- a/lib/github/auth/cli.rb
+++ b/lib/github/auth/cli.rb
@@ -3,7 +3,7 @@ module Github::Auth
   class CLI
     attr_reader :command, :usernames
 
-    COMMANDS = %w(add remove)
+    COMMANDS = %w(add remove list)
 
     def initialize(argv)
       @command   = argv.shift
@@ -11,7 +11,7 @@ def initialize(argv)
     end
 
     def execute
-      if COMMANDS.include?(command) && !usernames.empty?
+      if COMMANDS.include?(command)
         send command
       elsif command == '--version'
         print_version
@@ -23,15 +23,29 @@ def execute
     private
 
     def add
+      if usernames.empty?
+        print_usage
+        return
+      end
+
       on_keys_file :write!,
         "Adding #{keys.count} key(s) to '#{keys_file.path}'"
     end
 
     def remove
+      if usernames.empty?
+        print_usage
+        return
+      end
+
       on_keys_file :delete!,
         "Removing #{keys.count} key(s) from '#{keys_file.path}'"
     end
 
+    def list
+      puts "Added users: #{keys_file.github_users.join(', ')}"
+    end
+
     def on_keys_file(action, message)
       puts message
       rescue_keys_file_errors { keys_file.send action, keys }
diff --git a/lib/github/auth/keys_file.rb b/lib/github/auth/keys_file.rb
index bcca720..25db857 100644
--- a/lib/github/auth/keys_file.rb
+++ b/lib/github/auth/keys_file.rb
@@ -31,6 +31,12 @@ def delete!(keys)
       write_keys_file { |keys_file| keys_file.write new_content }
     end
 
+    def github_users
+      # http://rubular.com/r/zXCkewmm0i
+      regex = %r{github\.com/(\S+)}
+      keys_file_content.scan(regex).flatten.uniq.sort
+    end
+
     private
 
     def append_keys_file(&block)
diff --git a/spec/acceptance/github/auth/cli_spec.rb b/spec/acceptance/github/auth/cli_spec.rb
index ced94be..495b419 100644
--- a/spec/acceptance/github/auth/cli_spec.rb
+++ b/spec/acceptance/github/auth/cli_spec.rb
@@ -1,4 +1,5 @@
 require 'spec_helper'
+require 'support/capture_stdout'
 require 'support/mock_github_server'
 require 'github/auth'
 
@@ -32,5 +33,15 @@ def cli(argv)
 
       keys_file.unlink
     end
+
+    it 'lists users from the keys file' do
+      cli(%w(add chrishunt)).execute
+
+      output = capture_stdout do
+        cli(%w(list)).execute
+      end
+
+      expect(output).to include('chrishunt')
+    end
   end
 end
diff --git a/spec/support/capture_stdout.rb b/spec/support/capture_stdout.rb
new file mode 100644
index 0000000..3892054
--- /dev/null
+++ b/spec/support/capture_stdout.rb
@@ -0,0 +1,11 @@
+require 'stringio'
+
+def capture_stdout
+  captured_output = StringIO.new
+  real_stdout = $stdout
+  $stdout = captured_output
+  yield
+  captured_output.string
+ensure
+  $stdout = real_stdout
+end
diff --git a/spec/unit/github/auth/keys_file_spec.rb b/spec/unit/github/auth/keys_file_spec.rb
index 29554aa..ce175da 100644
--- a/spec/unit/github/auth/keys_file_spec.rb
+++ b/spec/unit/github/auth/keys_file_spec.rb
@@ -197,4 +197,22 @@
       end
     end
   end
+
+  describe '#github_users' do
+    let(:keys) {[
+      Github::Auth::Key.new('jay',   'abc123'),
+      Github::Auth::Key.new('chris', 'def456'),
+      Github::Auth::Key.new('chris', 'ghi789'),
+    ]}
+
+    before do
+      keys_file.write keys.join("\n")
+      keys_file.write "\n"
+      keys_file.rewind
+    end
+
+    it 'returns a uniq, ordered list of github users' do
+      expect(subject.github_users).to eq(%w(chris jay))
+    end
+  end
 end