diff --git a/activesupport/CHANGELOG b/activesupport/CHANGELOG
index 1a1cb9c275c0c390f45c0d368158b70c6ce866ae..69c2c0166a4bf06a6191e9fc3194f00ef78fdb7a 100644
--- a/activesupport/CHANGELOG
+++ b/activesupport/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Date, Time, and DateTime#to_json.  #8399 [wycats]
+
 * Simplify API of assert_difference by passing in an expression that is evaluated before and after the passed in block. See documenation for examples of new API. [Marcel Molina Jr.]
 
 * Added assert_difference and assert_no_difference to test/unit assertions [Tobias Luetke]
diff --git a/activesupport/lib/active_support/json/encoders/date.rb b/activesupport/lib/active_support/json/encoders/date.rb
new file mode 100644
index 0000000000000000000000000000000000000000..ee1a472f3fad8b4af0ab364c28197c3ad2ede618
--- /dev/null
+++ b/activesupport/lib/active_support/json/encoders/date.rb
@@ -0,0 +1,5 @@
+class Date
+  def to_json #:nodoc:
+    %("#{strftime("%m/%d/%Y")}")
+  end
+end
diff --git a/activesupport/lib/active_support/json/encoders/date_time.rb b/activesupport/lib/active_support/json/encoders/date_time.rb
new file mode 100644
index 0000000000000000000000000000000000000000..28cb18977d5a3d035f5374fac8c87bd723673b35
--- /dev/null
+++ b/activesupport/lib/active_support/json/encoders/date_time.rb
@@ -0,0 +1,5 @@
+class DateTime
+  def to_json #:nodoc:
+    %("#{strftime("%m/%d/%Y %H:%M:%S %Z")}")
+  end
+end
diff --git a/activesupport/lib/active_support/json/encoders/time.rb b/activesupport/lib/active_support/json/encoders/time.rb
new file mode 100644
index 0000000000000000000000000000000000000000..080e9392f1443d74c45f0af98c2dc78e90ade375
--- /dev/null
+++ b/activesupport/lib/active_support/json/encoders/time.rb
@@ -0,0 +1,5 @@
+class Time
+  def to_json #:nodoc:
+    %("#{strftime("%m/%d/%Y %H:%M:%S %Z")}")
+  end
+end
diff --git a/activesupport/test/json/encoding_test.rb b/activesupport/test/json/encoding_test.rb
index 149d11ce0f317ef9d67b7ce0fecc241077612e06..dbb96cb38ce455358295ba4b73882d834783676a 100644
--- a/activesupport/test/json/encoding_test.rb
+++ b/activesupport/test/json/encoding_test.rb
@@ -29,6 +29,10 @@ def initialize(a, b)
                    [ ActiveSupport::JSON::Variable.new('alert("foo")'), 'alert("foo")']]
   RegexpTests   = [[ /^a/, '/^a/' ], [/^\w{1,2}[a-z]+/ix, '/^\\w{1,2}[a-z]+/ix']]
 
+  DateTests     = [[ Date.new(2005,1,1), %("01/01/2005") ]]
+  TimeTests     = [[ Time.at(0), %("12/31/1969 16:00:00 #{Time.at(0).zone}") ]]
+  DateTimeTests = [[ Time.at(0), %("12/31/1969 16:00:00 #{Time.at(0).zone}") ]]
+
   constants.grep(/Tests$/).each do |class_tests|
     define_method("test_#{class_tests[0..-6].downcase}") do
       self.class.const_get(class_tests).each do |pair|