diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index 465b0c1e16..be829222ff 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,5 +1,8 @@
 ## Rails 3.2.0 (unreleased) ##
 
+* Module#synchronize is deprecated with no replacement.  Please use `monitor`
+  from ruby's standard library.
+
 *   (Date|DateTime|Time)#beginning_of_week accept an optional argument to
     be able to set the day at which weeks are assumed to start.
 
diff --git a/activesupport/lib/active_support/core_ext/module/synchronization.rb b/activesupport/lib/active_support/core_ext/module/synchronization.rb
index ed16c2f71b..061621c0ef 100644
--- a/activesupport/lib/active_support/core_ext/module/synchronization.rb
+++ b/activesupport/lib/active_support/core_ext/module/synchronization.rb
@@ -1,6 +1,7 @@
 require 'thread'
 require 'active_support/core_ext/module/aliasing'
 require 'active_support/core_ext/array/extract_options'
+require 'active_support/core_ext/module/deprecation'
 
 class Module
   # Synchronize access around a method, delegating synchronization to a
@@ -40,4 +41,5 @@ class Module
       alias_method_chain method, :synchronization
     end
   end
+  deprecate :synchronize
 end
diff --git a/activesupport/test/core_ext/module/synchronization_test.rb b/activesupport/test/core_ext/module/synchronization_test.rb
deleted file mode 100644
index 6c407e2260..0000000000
--- a/activesupport/test/core_ext/module/synchronization_test.rb
+++ /dev/null
@@ -1,89 +0,0 @@
-require 'thread'
-require 'abstract_unit'
-
-require 'active_support/core_ext/class/attribute_accessors'
-require 'active_support/core_ext/module/synchronization'
-
-class SynchronizationTest < Test::Unit::TestCase
-  def setup
-    @target = Class.new
-    @target.cattr_accessor :mutex, :instance_writer => false
-    @target.mutex = Mutex.new
-    @instance = @target.new
-  end
-
-  def test_synchronize_aliases_method_chain_with_synchronize
-    @target.module_eval do
-      attr_accessor :value
-      synchronize :value, :with => :mutex
-    end
-    assert_respond_to @instance, :value_with_synchronization
-    assert_respond_to @instance, :value_without_synchronization
-  end
-
-  def test_synchronize_does_not_change_behavior
-    @target.module_eval do
-      attr_accessor :value
-      synchronize :value, :with => :mutex
-    end
-    expected = "some state"
-    @instance.value = expected
-    assert_equal expected, @instance.value
-  end
-
-  def test_synchronize_with_no_mutex_raises_an_argument_error
-    assert_raise(ArgumentError) do
-      @target.synchronize :to_s
-    end
-  end
-
-  def test_double_synchronize_raises_an_argument_error
-    @target.synchronize :to_s, :with => :mutex
-    assert_raise(ArgumentError) do
-      @target.synchronize :to_s, :with => :mutex
-    end
-  end
-
-  def dummy_sync
-    dummy = Object.new
-    def dummy.synchronize
-      @sync_count ||= 0
-      @sync_count += 1
-      yield
-    end
-    def dummy.sync_count; @sync_count; end
-    dummy
-  end
-
-  def test_mutex_is_entered_during_method_call
-    @target.mutex = dummy_sync
-    @target.synchronize :to_s, :with => :mutex
-    @instance.to_s
-    @instance.to_s
-    assert_equal 2, @target.mutex.sync_count
-  end
-
-  def test_can_synchronize_method_with_punctuation
-    @target.module_eval do
-      def dangerous?
-        @dangerous
-      end
-      def dangerous!
-        @dangerous = true
-      end
-    end
-    @target.synchronize :dangerous?, :dangerous!, :with => :mutex
-    @instance.dangerous!
-    assert @instance.dangerous?
-  end
-
-  def test_can_synchronize_singleton_methods
-    @target.mutex = dummy_sync
-    class << @target
-      synchronize :to_s, :with => :mutex
-    end
-    assert_respond_to @target, :to_s_without_synchronization
-    assert_nothing_raised { @target.to_s; @target.to_s }
-    assert_equal 2, @target.mutex.sync_count
-  end
-end