diff --git a/activesupport/CHANGELOG b/activesupport/CHANGELOG
index 757cb1da04..fed977775e 100644
--- a/activesupport/CHANGELOG
+++ b/activesupport/CHANGELOG
@@ -1,5 +1,7 @@
 *2.3.0 [Edge]*
 
+* TimeWithZone#xmlschema accepts optional fraction_digits argument [#1725 state:resolved] [Nicholas Dainty]
+
 * Object#tap shim for Ruby < 1.8.7. Similar to Object#returning, tap yields self then returns self.  [Jeremy Kemper]
     array.select { ... }.tap(&:inspect).map { ... }
 
diff --git a/activesupport/lib/active_support/time_with_zone.rb b/activesupport/lib/active_support/time_with_zone.rb
index 99be89fdf0..ec28f9801a 100644
--- a/activesupport/lib/active_support/time_with_zone.rb
+++ b/activesupport/lib/active_support/time_with_zone.rb
@@ -99,8 +99,12 @@ module ActiveSupport
       "#{time.strftime('%a, %d %b %Y %H:%M:%S')} #{zone} #{formatted_offset}"
     end
 
-    def xmlschema
-      "#{time.strftime("%Y-%m-%dT%H:%M:%S")}#{formatted_offset(true, 'Z')}"
+    def xmlschema(fraction_digits = 0)
+      fraction = if fraction_digits > 0
+        ".%i" % time.usec.to_s[0, fraction_digits]
+      end
+
+      "#{time.strftime("%Y-%m-%dT%H:%M:%S")}#{fraction}#{formatted_offset(true, 'Z')}"
     end
     alias_method :iso8601, :xmlschema
 
diff --git a/activesupport/test/core_ext/time_with_zone_test.rb b/activesupport/test/core_ext/time_with_zone_test.rb
index 7c8fb7dd94..4dc1fec559 100644
--- a/activesupport/test/core_ext/time_with_zone_test.rb
+++ b/activesupport/test/core_ext/time_with_zone_test.rb
@@ -105,6 +105,15 @@ class TimeWithZoneTest < Test::Unit::TestCase
     end
   end
 
+  def test_xmlschema_with_fractional_seconds
+    silence_warnings do # silence warnings raised by tzinfo gem
+      @twz += 0.123456 # advance the time by a fraction of a second
+      assert_equal "1999-12-31T19:00:00.123-05:00", @twz.xmlschema(3)
+      assert_equal "1999-12-31T19:00:00.123456-05:00", @twz.xmlschema(6)
+      assert_equal "1999-12-31T19:00:00.123456-05:00", @twz.xmlschema(12)
+    end
+  end
+
   def test_to_yaml
     silence_warnings do # silence warnings raised by tzinfo gem
       assert_equal "--- 1999-12-31 19:00:00 -05:00\n", @twz.to_yaml