diff --git a/Doc/library/contextlib.rst b/Doc/library/contextlib.rst
index b6ec6b8c876bee..0fe3206540e80d 100644
--- a/Doc/library/contextlib.rst
+++ b/Doc/library/contextlib.rst
@@ -485,6 +485,9 @@ Functions and classes provided:
           # the with statement, even if attempts to open files later
           # in the list raise an exception
 
+   The :meth:`__enter__` method returns the :class:`ExitStack` instance, and
+   performs no additional operations.
+
    Each instance maintains a stack of registered callbacks that are called in
    reverse order when the instance is closed (either explicitly or implicitly
    at the end of a :keyword:`with` statement). Note that callbacks are *not*