diff --git a/Lib/unittest/case.py b/Lib/unittest/case.py
--- a/Lib/unittest/case.py
+++ b/Lib/unittest/case.py
@@ -7,6 +7,12 @@ import pprint
 import re
 import warnings
 import collections
+import contextlib
+
+try:
+    import threading
+except ImportError:
+    import dummy_threading as threading
 
 from . import result
 from .util import (strclass, safe_repr, _count_diff_all_purpose,
@@ -42,16 +48,61 @@ class _UnexpectedSuccess(Exception):
     The test was supposed to fail, but it didn't!
     """
 
+class _ShouldStop(Exception):
+    """
+    The test should stop.
+    """
+
 
 class _Outcome(object):
-    def __init__(self):
+    def __init__(self, result=None):
+        self.result = result
         self.success = True
-        self.skipped = None
-        self.unexpectedSuccess = None
-        self.expectedFailure = None
+        self.skipped = []
+        self.unexpectedSuccesses = []
+        self.expectedFailures = []
         self.errors = []
         self.failures = []
 
+    @contextlib.contextmanager
+    def testPartExecutor(self, test_case, isTest=False):
+        try:
+            yield
+        except KeyboardInterrupt:
+            raise
+        except SkipTest as e:
+            self.success = False
+            self.skipped.append((test_case, str(e)))
+        except _ShouldStop:
+            pass
+        except _UnexpectedSuccess:
+            exc_info = sys.exc_info()
+            self.success = False
+            if isTest:
+                self.unexpectedSuccesses.append((test_case, exc_info))
+            else:
+                self.errors.append((test_case, exc_info))
+        except _ExpectedFailure:
+            self.success = False
+            exc_info = sys.exc_info()
+            if isTest:
+                self.expectedFailures.append((test_case, exc_info))
+            else:
+                self.errors.append((test_case, exc_info))
+        except test_case.failureException:
+            self.success = False
+            # If the test is expecting a failure, we really want to
+            # stop now and register the expected failure.
+            if getattr(_context, 'expecting_failure', 0):
+                raise
+            self.failures.append((test_case, sys.exc_info()))
+        except:
+            self.success = False
+            # See above.
+            if getattr(_context, 'expecting_failure', 0):
+                raise
+            self.errors.append((test_case, sys.exc_info()))
+
 
 def _id(obj):
     return obj
@@ -88,14 +139,23 @@ def skipUnless(condition, reason):
         return skip(reason)
     return _id
 
+# This unfortunate hack workarounds the fact that expectedFailure() doesn't
+# communicate with the rest of the test machinery.
+_context = threading.local()
 
 def expectedFailure(func):
     @functools.wraps(func)
     def wrapper(*args, **kwargs):
         try:
+            _context.expecting_failure += 1
+        except AttributeError:
+            _context.expecting_failure = 1
+        try:
             func(*args, **kwargs)
         except Exception:
             raise _ExpectedFailure(sys.exc_info())
+        finally:
+            _context.expecting_failure -= 1
         raise _UnexpectedSuccess
     return wrapper
 
@@ -271,7 +331,7 @@ class TestCase(object):
            not have a method with the specified name.
         """
         self._testMethodName = methodName
-        self._outcomeForDoCleanups = None
+        self._outcome = None
         self._testMethodDoc = 'No test'
         try:
             testMethod = getattr(self, methodName)
@@ -284,6 +344,7 @@ class TestCase(object):
         else:
             self._testMethodDoc = testMethod.__doc__
         self._cleanups = []
+        self._subtest = None
 
         # Map types to custom assertEqual functions that will compare
         # instances of said type in more detail to generate a more useful
@@ -371,44 +432,32 @@ class TestCase(object):
         return "<%s testMethod=%s>" % \
                (strclass(self.__class__), self._testMethodName)
 
-    def _addSkip(self, result, reason):
+    def _addSkip(self, result, test_case, reason):
         addSkip = getattr(result, 'addSkip', None)
         if addSkip is not None:
-            addSkip(self, reason)
+            addSkip(test_case, reason)
         else:
             warnings.warn("TestResult has no addSkip method, skips not reported",
                           RuntimeWarning, 2)
-            result.addSuccess(self)
+            result.addSuccess(test_case)
 
-    def _executeTestPart(self, function, outcome, isTest=False):
+    @contextlib.contextmanager
+    def subTest(self, **params):
+        parent = self._subtest
+        if parent is None:
+            params_map = collections.ChainMap(params)
+        else:
+            params_map = parent.params.new_child(params)
+        self._subtest = _SubTest(self, params_map, parent)
         try:
-            function()
-        except KeyboardInterrupt:
-            raise
-        except SkipTest as e:
-            outcome.success = False
-            outcome.skipped = str(e)
-        except _UnexpectedSuccess:
-            exc_info = sys.exc_info()
-            outcome.success = False
-            if isTest:
-                outcome.unexpectedSuccess = exc_info
-            else:
-                outcome.errors.append(exc_info)
-        except _ExpectedFailure:
-            outcome.success = False
-            exc_info = sys.exc_info()
-            if isTest:
-                outcome.expectedFailure = exc_info
-            else:
-                outcome.errors.append(exc_info)
-        except self.failureException:
-            outcome.success = False
-            outcome.failures.append(sys.exc_info())
-            exc_info = sys.exc_info()
-        except:
-            outcome.success = False
-            outcome.errors.append(sys.exc_info())
+            with self._outcome.testPartExecutor(self._subtest, isTest=True):
+                yield
+            if not self._outcome.success:
+                result = self._outcome.result
+                if result is not None and result.failfast:
+                    raise _ShouldStop
+        finally:
+            self._subtest = parent
 
     def run(self, result=None):
         orig_result = result
@@ -427,46 +476,49 @@ class TestCase(object):
             try:
                 skip_why = (getattr(self.__class__, '__unittest_skip_why__', '')
                             or getattr(testMethod, '__unittest_skip_why__', ''))
-                self._addSkip(result, skip_why)
+                self._addSkip(result, self, skip_why)
             finally:
                 result.stopTest(self)
             return
         try:
-            outcome = _Outcome()
-            self._outcomeForDoCleanups = outcome
+            outcome = _Outcome(result)
+            self._outcome = outcome
 
-            self._executeTestPart(self.setUp, outcome)
+            with outcome.testPartExecutor(self):
+                self.setUp()
             if outcome.success:
-                self._executeTestPart(testMethod, outcome, isTest=True)
-                self._executeTestPart(self.tearDown, outcome)
+                with outcome.testPartExecutor(self, isTest=True):
+                    testMethod()
+                with outcome.testPartExecutor(self):
+                    self.tearDown()
 
             self.doCleanups()
             if outcome.success:
                 result.addSuccess(self)
             else:
-                if outcome.skipped is not None:
-                    self._addSkip(result, outcome.skipped)
-                for exc_info in outcome.errors:
-                    result.addError(self, exc_info)
-                for exc_info in outcome.failures:
-                    result.addFailure(self, exc_info)
-                if outcome.unexpectedSuccess is not None:
+                for test, reason in outcome.skipped:
+                    self._addSkip(result, test, reason)
+                for test, exc_info in outcome.errors:
+                    result.addError(test, exc_info)
+                for test, exc_info in outcome.failures:
+                    result.addFailure(test, exc_info)
+                for test, exc_info in outcome.unexpectedSuccesses:
                     addUnexpectedSuccess = getattr(result, 'addUnexpectedSuccess', None)
                     if addUnexpectedSuccess is not None:
-                        addUnexpectedSuccess(self)
+                        addUnexpectedSuccess(test)
                     else:
                         warnings.warn("TestResult has no addUnexpectedSuccess method, reporting as failures",
                                       RuntimeWarning)
-                        result.addFailure(self, outcome.unexpectedSuccess)
+                        result.addFailure(test, exc_info)
 
-                if outcome.expectedFailure is not None:
+                for test, exc_info in outcome.expectedFailures:
                     addExpectedFailure = getattr(result, 'addExpectedFailure', None)
                     if addExpectedFailure is not None:
-                        addExpectedFailure(self, outcome.expectedFailure)
+                        addExpectedFailure(test, exc_info)
                     else:
                         warnings.warn("TestResult has no addExpectedFailure method, reporting as passes",
                                       RuntimeWarning)
-                        result.addSuccess(self)
+                        result.addSuccess(test)
             return result
         finally:
             result.stopTest(self)
@@ -478,11 +530,11 @@ class TestCase(object):
     def doCleanups(self):
         """Execute all cleanup functions. Normally called for you after
         tearDown."""
-        outcome = self._outcomeForDoCleanups or _Outcome()
+        outcome = self._outcome or _Outcome()
         while self._cleanups:
             function, args, kwargs = self._cleanups.pop()
-            part = lambda: function(*args, **kwargs)
-            self._executeTestPart(part, outcome)
+            with outcome.testPartExecutor(self):
+                function(*args, **kwargs)
 
         # return this for backwards compatibility
         # even though we no longer us it internally
@@ -1213,3 +1265,35 @@ class FunctionTestCase(TestCase):
             return self._description
         doc = self._testFunc.__doc__
         return doc and doc.split("\n")[0].strip() or None
+
+
+class _SubTest(TestCase):
+
+    def __init__(self, test_case, params, parent=None):
+        super().__init__()
+        self.test_case = test_case
+        self.params = params
+        self.failureException = test_case.failureException
+
+    def runTest(self):
+        raise NotImplementedError("subtests cannot be run directly")
+
+    def _paramsDescription(self):
+        if self.params:
+            return ', '.join(
+                "{}={!r}".format(k, v)
+                for (k, v) in sorted(self.params.items()))
+        else:
+            return '<subtest>'
+
+    def id(self):
+        return "{} ({})".format(self.test_case.id(), self._paramsDescription())
+
+    def shortDescription(self):
+        """Returns a one-line description of the subtest, or None if no
+        description has been provided.
+        """
+        return self.test_case.shortDescription()
+
+    def __str__(self):
+        return "{} ({})".format(self.test_case, self._paramsDescription())
diff --git a/Lib/unittest/test/test_case.py b/Lib/unittest/test/test_case.py
--- a/Lib/unittest/test/test_case.py
+++ b/Lib/unittest/test/test_case.py
@@ -297,6 +297,55 @@ class Test_TestCase(unittest.TestCase, T
 
         Foo('test').run()
 
+    def test_run_call_order__subtests(self):
+        events = []
+        result = LoggingResult(events)
+
+        class Foo(Test.LoggingTestCase):
+            def test(self):
+                super(Foo, self).test()
+                for i in range(1, 4):
+                    with self.subTest(i=i):
+                        if i == 1:
+                            self.fail('failure')
+                        for j in range(0, 5):
+                            with self.subTest(j=j):
+                                if i * j == 6:
+                                    raise RuntimeError('raised by Foo.test')
+                self.fail('failure')
+
+        # Order is the following:
+        # i=1 => failure
+        # i=2, j=3 => error
+        # i=3, j=2 => error
+        # toplevel => failure
+        # However, errors and failures get accumulated at the end of the
+        # run() method, regardless of order.
+        expected = ['startTest', 'setUp', 'test', 'tearDown',
+                    'addError', 'addError', 'addFailure', 'addFailure',
+                    'stopTest']
+        Foo(events).run(result)
+        self.assertEqual(events, expected)
+
+    def test_run_call_order__subtests_failfast(self):
+        events = []
+        result = LoggingResult(events)
+        result.failfast = True
+
+        class Foo(Test.LoggingTestCase):
+            def test(self):
+                super(Foo, self).test()
+                with self.subTest(i=1):
+                    self.fail('failure')
+                with self.subTest(i=2):
+                    self.fail('failure')
+                self.fail('failure')
+
+        expected = ['startTest', 'setUp', 'test', 'tearDown',
+                    'addFailure', 'stopTest']
+        Foo(events).run(result)
+        self.assertEqual(events, expected)
+
     # "This class attribute gives the exception raised by the test() method.
     # If a test framework needs to use a specialized exception, possibly to
     # carry additional information, it must subclass this exception in
diff --git a/Lib/unittest/test/test_result.py b/Lib/unittest/test/test_result.py
--- a/Lib/unittest/test/test_result.py
+++ b/Lib/unittest/test/test_result.py
@@ -234,6 +234,31 @@ class Test_TestResult(unittest.TestCase)
                 'testGetDescriptionWithoutDocstring (' + __name__ +
                 '.Test_TestResult)')
 
+    def testGetSubTestDescriptionWithoutDocstring(self):
+        with self.subTest(foo=1, bar=2):
+            result = unittest.TextTestResult(None, True, 1)
+            self.assertEqual(
+                    result.getDescription(self._subtest),
+                    'testGetSubTestDescriptionWithoutDocstring (' + __name__ +
+                    '.Test_TestResult) (bar=2, foo=1)')
+
+    def testGetSubTestDescriptionWithoutDocstringAndParams(self):
+        with self.subTest():
+            result = unittest.TextTestResult(None, True, 1)
+            self.assertEqual(
+                    result.getDescription(self._subtest),
+                    'testGetSubTestDescriptionWithoutDocstringAndParams '
+                    '(' + __name__ + '.Test_TestResult) (<subtest>)')
+
+    def testGetNestedSubTestDescriptionWithoutDocstring(self):
+        with self.subTest(foo=1):
+            with self.subTest(bar=2):
+                result = unittest.TextTestResult(None, True, 1)
+                self.assertEqual(
+                        result.getDescription(self._subtest),
+                        'testGetNestedSubTestDescriptionWithoutDocstring '
+                        '(' + __name__ + '.Test_TestResult) (bar=2, foo=1)')
+
     @unittest.skipIf(sys.flags.optimize >= 2,
                      "Docstrings are omitted with -O2 and above")
     def testGetDescriptionWithOneLineDocstring(self):
@@ -247,6 +272,18 @@ class Test_TestResult(unittest.TestCase)
 
     @unittest.skipIf(sys.flags.optimize >= 2,
                      "Docstrings are omitted with -O2 and above")
+    def testGetSubTestDescriptionWithOneLineDocstring(self):
+        """Tests getDescription() for a method with a docstring."""
+        result = unittest.TextTestResult(None, True, 1)
+        with self.subTest(foo=1, bar=2):
+            self.assertEqual(
+                result.getDescription(self._subtest),
+               ('testGetSubTestDescriptionWithOneLineDocstring '
+                '(' + __name__ + '.Test_TestResult) (bar=2, foo=1)\n'
+                'Tests getDescription() for a method with a docstring.'))
+
+    @unittest.skipIf(sys.flags.optimize >= 2,
+                     "Docstrings are omitted with -O2 and above")
     def testGetDescriptionWithMultiLineDocstring(self):
         """Tests getDescription() for a method with a longer docstring.
         The second line of the docstring.
@@ -259,6 +296,21 @@ class Test_TestResult(unittest.TestCase)
                 'Tests getDescription() for a method with a longer '
                 'docstring.'))
 
+    @unittest.skipIf(sys.flags.optimize >= 2,
+                     "Docstrings are omitted with -O2 and above")
+    def testGetSubTestDescriptionWithMultiLineDocstring(self):
+        """Tests getDescription() for a method with a longer docstring.
+        The second line of the docstring.
+        """
+        result = unittest.TextTestResult(None, True, 1)
+        with self.subTest(foo=1, bar=2):
+            self.assertEqual(
+                result.getDescription(self._subtest),
+               ('testGetSubTestDescriptionWithMultiLineDocstring '
+                '(' + __name__ + '.Test_TestResult) (bar=2, foo=1)\n'
+                'Tests getDescription() for a method with a longer '
+                'docstring.'))
+
     def testStackFrameTrimming(self):
         class Frame(object):
             class tb_frame(object):
diff --git a/Lib/unittest/test/test_runner.py b/Lib/unittest/test/test_runner.py
--- a/Lib/unittest/test/test_runner.py
+++ b/Lib/unittest/test/test_runner.py
@@ -5,6 +5,7 @@ import pickle
 import subprocess
 
 import unittest
+from unittest.case import _Outcome
 
 from .support import LoggingResult, ResultWithNoStartTestRunStopTestRun
 
@@ -42,12 +43,8 @@ class TestCleanUp(unittest.TestCase):
             def testNothing(self):
                 pass
 
-        class MockOutcome(object):
-            success = True
-            errors = []
-
         test = TestableTest('testNothing')
-        test._outcomeForDoCleanups = MockOutcome
+        outcome = test._outcome = _Outcome()
 
         exc1 = Exception('foo')
         exc2 = Exception('bar')
@@ -61,9 +58,10 @@ class TestCleanUp(unittest.TestCase):
         test.addCleanup(cleanup2)
 
         self.assertFalse(test.doCleanups())
-        self.assertFalse(MockOutcome.success)
+        self.assertFalse(outcome.success)
 
-        (Type1, instance1, _), (Type2, instance2, _) = reversed(MockOutcome.errors)
+        ((_, (Type1, instance1, _)),
+         (_, (Type2, instance2, _))) = reversed(outcome.errors)
         self.assertEqual((Type1, instance1), (Exception, exc1))
         self.assertEqual((Type2, instance2), (Exception, exc2))
 
diff --git a/Lib/unittest/test/test_skipping.py b/Lib/unittest/test/test_skipping.py
--- a/Lib/unittest/test/test_skipping.py
+++ b/Lib/unittest/test/test_skipping.py
@@ -29,6 +29,31 @@ class Test_TestSkipping(unittest.TestCas
         self.assertEqual(result.skipped, [(test, "testing")])
         self.assertEqual(result.testsRun, 1)
 
+    def test_skipping_subtests(self):
+        class Foo(unittest.TestCase):
+            def test_skip_me(self):
+                with self.subTest(a=1):
+                    with self.subTest(b=2):
+                        self.skipTest("skip 1")
+                    self.skipTest("skip 2")
+                self.skipTest("skip 3")
+        events = []
+        result = LoggingResult(events)
+        test = Foo("test_skip_me")
+        test.run(result)
+        self.assertEqual(events, ['startTest', 'addSkip', 'addSkip',
+                                  'addSkip', 'stopTest'])
+        self.assertEqual(len(result.skipped), 3)
+        subtest, msg = result.skipped[0]
+        self.assertEqual(msg, "skip 1")
+        self.assertIsInstance(subtest, unittest.TestCase)
+        self.assertIsNot(subtest, test)
+        subtest, msg = result.skipped[1]
+        self.assertEqual(msg, "skip 2")
+        self.assertIsInstance(subtest, unittest.TestCase)
+        self.assertIsNot(subtest, test)
+        self.assertEqual(result.skipped[2], (test, "skip 3"))
+
     def test_skipping_decorators(self):
         op_table = ((unittest.skipUnless, False, True),
                     (unittest.skipIf, True, False))
@@ -95,6 +120,30 @@ class Test_TestSkipping(unittest.TestCas
         self.assertEqual(result.expectedFailures[0][0], test)
         self.assertTrue(result.wasSuccessful())
 
+    def test_expected_failure_subtests(self):
+        # A failure in any subtest counts as the expected failure of the
+        # whole test.
+        class Foo(unittest.TestCase):
+            @unittest.expectedFailure
+            def test_die(self):
+                with self.subTest():
+                    # This one succeeds
+                    pass
+                with self.subTest():
+                    self.fail("help me!")
+                with self.subTest():
+                    # This one doesn't get executed
+                    self.fail("shouldn't come here")
+        events = []
+        result = LoggingResult(events)
+        test = Foo("test_die")
+        test.run(result)
+        self.assertEqual(events,
+                         ['startTest', 'addExpectedFailure', 'stopTest'])
+        self.assertEqual(len(result.expectedFailures), 1)
+        self.assertIs(result.expectedFailures[0][0], test)
+        self.assertTrue(result.wasSuccessful())
+
     def test_unexpected_success(self):
         class Foo(unittest.TestCase):
             @unittest.expectedFailure
@@ -110,6 +159,28 @@ class Test_TestSkipping(unittest.TestCas
         self.assertEqual(result.unexpectedSuccesses, [test])
         self.assertTrue(result.wasSuccessful())
 
+    def test_unexpected_success_subtests(self):
+        # Success in all subtests counts as the unexpected success of
+        # the whole test.
+        class Foo(unittest.TestCase):
+            @unittest.expectedFailure
+            def test_die(self):
+                with self.subTest():
+                    # This one succeeds
+                    pass
+                with self.subTest():
+                    # So does this one
+                    pass
+        events = []
+        result = LoggingResult(events)
+        test = Foo("test_die")
+        test.run(result)
+        self.assertEqual(events,
+                         ['startTest', 'addUnexpectedSuccess', 'stopTest'])
+        self.assertFalse(result.failures)
+        self.assertEqual(result.unexpectedSuccesses, [test])
+        self.assertTrue(result.wasSuccessful())
+
     def test_skip_doesnt_run_setup(self):
         class Foo(unittest.TestCase):
             wasSetUp = False