diff --git a/ChangeLog b/ChangeLog
index 7c3f53d89b..fe4e018c1e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Mon May 20 03:16:52 2013  Zachary Scott  <zachary@zacharyscott.net>
+
+	* lib/pp.rb: Document PP::ObjectMixin [Fixes GH-312]
+
 Sun May 19 23:52:22 2013  Ayumu AIZAWA  <ayumu.aizawa@gmail.com>
 
 	* test/webrick/test_htmlutils.rb: add test for WEBrick::HTMLUtils.
diff --git a/lib/pp.rb b/lib/pp.rb
index 18cc473509..b7dbef6ca1 100644
--- a/lib/pp.rb
+++ b/lib/pp.rb
@@ -300,6 +300,34 @@ class PP < PrettyPrint
     include PPMethods
   end
 
+  # Allows you to implement pretty print in your own class, for example:
+  #     require 'pp'
+  #     
+  #     class Cat
+  #       include PP::ObjectMixin
+  #     
+  #       attr_accessor :name, :age, :color
+  #     
+  #       def initialize name
+  #         @name = name
+  #       end
+  #     
+  #       def pretty_print q
+  #         q.pp_object self
+  #       end
+  #       alias inspect pretty_print_inspect
+  #     
+  #     end
+  #
+  # In order to use this class, try the following:
+  #
+  #     ginger = Cat.new("ginger")
+  #     p ginger
+  #     #=> #<Cat:0x007f8dfb994900 @name="ginger">
+  #     ginger.age = 2
+  #     ginger.color = "red"
+  #     p ginger
+  #     #=> #<Cat:0x007f8dfb994900 @age=2, @color="red", @name="ginger">
   module ObjectMixin
     # 1. specific pretty_print
     # 2. specific inspect