diff -r 462470859e57 Doc/library/concurrent.futures.rst
--- a/Doc/library/concurrent.futures.rst	Sat Apr 26 19:01:47 2014 -0400
+++ b/Doc/library/concurrent.futures.rst	Sun Apr 27 19:26:12 2014 +0300
@@ -175,6 +175,8 @@
    An :class:`Executor` subclass that executes calls asynchronously using a pool
    of at most *max_workers* processes.  If *max_workers* is ``None`` or not
    given, it will default to the number of processors on the machine.
+   If *max_workers* is lower or equal to ``0``, than a :exc:`ValueError`
+   will be raised.
 
    .. versionchanged:: 3.3
       When one of the worker processes terminates abruptly, a
diff -r 462470859e57 Lib/concurrent/futures/process.py
--- a/Lib/concurrent/futures/process.py	Sat Apr 26 19:01:47 2014 -0400
+++ b/Lib/concurrent/futures/process.py	Sun Apr 27 19:26:12 2014 +0300
@@ -334,6 +334,9 @@
         if max_workers is None:
             self._max_workers = os.cpu_count() or 1
         else:
+            if max_workers <= 0:
+                raise ValueError("max_workers must be greater than 0")
+
             self._max_workers = max_workers
 
         # Make the call queue slightly larger than the number of processes to
diff -r 462470859e57 Lib/concurrent/futures/thread.py
--- a/Lib/concurrent/futures/thread.py	Sat Apr 26 19:01:47 2014 -0400
+++ b/Lib/concurrent/futures/thread.py	Sun Apr 27 19:26:12 2014 +0300
@@ -87,6 +87,9 @@
             max_workers: The maximum number of threads that can be used to
                 execute the given calls.
         """
+        if max_workers <= 0:
+            raise ValueError("max_workers must be greater than 0")
+
         self._max_workers = max_workers
         self._work_queue = queue.Queue()
         self._threads = set()
diff -r 462470859e57 Lib/test/test_concurrent_futures.py
--- a/Lib/test/test_concurrent_futures.py	Sat Apr 26 19:01:47 2014 -0400
+++ b/Lib/test/test_concurrent_futures.py	Sun Apr 27 19:26:12 2014 +0300
@@ -437,6 +437,13 @@
         self.executor.shutdown(wait=True)
         self.assertCountEqual(finished, range(10))
 
+    def test_max_workers_negative(self):
+        for number in (0, -1):
+            with self.assertRaisesRegexp(ValueError,
+                                         "max_workers must be greater "
+                                         "than 0"):
+                self.executor_type(max_workers=number)
+
 
 class ProcessPoolExecutorTest(ProcessPoolMixin, ExecutorTest, unittest.TestCase):
     def test_killed_child(self):
@@ -451,6 +458,16 @@
         # Submitting other jobs fails as well.
         self.assertRaises(BrokenProcessPool, self.executor.submit, pow, 2, 8)
 
+    def test_max_workers_negative(self):
+        for number in (0, -1):
+            with self.assertRaisesRegexp(ValueError,
+                                         "max_workers must be greater "
+                                         "than 0"):
+                try:
+                    self.executor_type(max_workers=number)
+                except NotImplementedError as e:
+                    self.skipTest(str(e))
+
 
 class FutureTests(unittest.TestCase):
     def test_done_callback_with_result(self):