diff --git a/activerecord/lib/active_record/named_scope.rb b/activerecord/lib/active_record/named_scope.rb
index 7397d702792e6..d7e152ed1da1d 100644
--- a/activerecord/lib/active_record/named_scope.rb
+++ b/activerecord/lib/active_record/named_scope.rb
@@ -101,7 +101,7 @@ def named_scope(name, options = {}, &block)
     
     class Scope
       attr_reader :proxy_scope, :proxy_options
-      NON_DELEGATE_METHODS = %w(nil? send object_id class extend find count sum average maximum minimum paginate first last empty? any? respond_to?).to_set
+      NON_DELEGATE_METHODS = %w(nil? send object_id class extend find size count sum average maximum minimum paginate first last empty? any? respond_to?).to_set
       [].methods.each do |m|
         unless m =~ /^__/ || NON_DELEGATE_METHODS.include?(m.to_s)
           delegate m, :to => :proxy_found
@@ -136,6 +136,10 @@ def last(*args)
         end
       end
 
+      def size
+        @found ? @found.length : count
+      end
+
       def empty?
         @found ? @found.empty? : count.zero?
       end
diff --git a/activerecord/test/cases/named_scope_test.rb b/activerecord/test/cases/named_scope_test.rb
index acc3b3016a3f7..444debd255a74 100644
--- a/activerecord/test/cases/named_scope_test.rb
+++ b/activerecord/test/cases/named_scope_test.rb
@@ -256,4 +256,19 @@ def test_rand_should_select_a_random_object_from_proxy
   def test_should_use_where_in_query_for_named_scope
     assert_equal Developer.find_all_by_name('Jamis'), Developer.find_all_by_id(Developer.jamises)
   end
+
+  def test_size_should_use_count_when_results_are_not_loaded
+    topics = Topic.base
+    assert_queries(1) do
+      assert_sql(/COUNT/i) { topics.size }
+    end
+  end
+
+  def test_size_should_use_length_when_results_are_loaded
+    topics = Topic.base
+    topics.reload # force load
+    assert_no_queries do
+      topics.size # use loaded (no query)
+    end
+  end
 end