diff -r 377bd6e0f61c Lib/unittest/mock.py
--- a/Lib/unittest/mock.py	Mon Sep 09 22:40:13 2013 -0700
+++ b/Lib/unittest/mock.py	Thu Sep 26 02:29:42 2013 -0700
@@ -48,6 +48,18 @@
     # The base class for all mocks is NonCallableMock
     return issubclass(type(obj), NonCallableMock)
 
+def _is_namedtuple_mock(obj):
+    return (
+        _is_instance_mock(obj) and
+        isinstance(obj._spec_class, type) and
+        issubclass(obj._spec_class, tuple) and
+        # namedtuples directly inherit from tuple so the best we can do
+        # is assume if it maintains the interface of namedtuple and
+        # subclasses tuple, that it is a namedtuple
+        hasattr(obj._spec_class, '_asdict') and
+        hasattr(obj._spec_class, '_fields') and
+        hasattr(obj._spec_class, '_replace')
+    )
 
 def _is_exception(obj):
     return (
@@ -1664,6 +1676,9 @@
     '__sizeof__': lambda self: object.__sizeof__(self),
 }
 
+def _calculate_namedtuple_length(obj):
+    return len(obj._spec_class._fields)
+
 _return_values = {
     '__lt__': NotImplemented,
     '__gt__': NotImplemented,
@@ -1714,15 +1729,21 @@
 
 
 def _set_return_value(mock, method, name):
+    # mocks are by default length 0. For namedtuples this is an
+    # issue because that means they will be falsey by default.
+    if name == '__len__' and _is_namedtuple_mock(mock):
+        method.return_value = _calculate_namedtuple_length(mock)
+        return
+
     fixed = _return_values.get(name, DEFAULT)
     if fixed is not DEFAULT:
         method.return_value = fixed
         return
 
-    return_calulator = _calculate_return_value.get(name)
-    if return_calulator is not None:
+    return_calculator = _calculate_return_value.get(name)
+    if return_calculator is not None:
         try:
-            return_value = return_calulator(mock)
+            return_value = return_calculator(mock)
         except AttributeError:
             # XXXX why do we return AttributeError here?
             #      set it as a side_effect instead?
diff -r 377bd6e0f61c Lib/unittest/test/testmock/testhelpers.py
--- a/Lib/unittest/test/testmock/testhelpers.py	Mon Sep 09 22:40:13 2013 -0700
+++ b/Lib/unittest/test/testmock/testhelpers.py	Thu Sep 26 02:29:42 2013 -0700
@@ -5,6 +5,8 @@
     Mock, ANY, _CallList, patch, PropertyMock
 )
 
+from collections import namedtuple
+
 from datetime import datetime
 
 class SomeClass(object):
@@ -480,6 +482,27 @@
         self.assertRaises(AttributeError, getattr, mock.attr, 'foo')
 
 
+    def test_length_of_namedtuple(self):
+        Foo = namedtuple('Foo', 'a b c')
+
+        mock = create_autospec(Foo)
+        self.assertEquals(3, len(mock))
+
+
+    def test_truthiness_of_namedtuple_with_field(self):
+        Foo = namedtuple('Foo', 'bar')
+
+        mock = create_autospec(Foo)
+        self.assertEquals(True, bool(mock))
+
+
+    def test_truthiness_of_namedtuple_without_field(self):
+        Foo = namedtuple('Foo', '')
+
+        mock = create_autospec(Foo)
+        self.assertEquals(False, bool(mock))
+
+
     def test_method_calls(self):
         class Sub(SomeClass):
             attr = SomeClass()