diff -r 395904f70d6a Doc/library/configparser.rst
--- a/Doc/library/configparser.rst	Fri Mar 21 11:24:40 2014 -0400
+++ b/Doc/library/configparser.rst	Fri Mar 21 08:47:31 2014 -0700
@@ -310,7 +310,8 @@
    ``home_dir`` (``/Users`` in this case).  ``%(my_dir)s`` in effect would
    resolve to ``/Users/lumberjack``.  All interpolations are done on demand so
    keys used in the chain of references do not have to be specified in any
-   specific order in the configuration file.
+   specific order in the configuration file. To use a bare ``%`` the user
+   can escape it by using ``%%``.
 
    With ``interpolation`` set to ``None``, the parser would simply return
    ``%(my_dir)s/Pictures`` as the value of ``my_pictures`` and
@@ -323,7 +324,8 @@
    using ``${section:option}`` to denote a value from a foreign section.
    Interpolation can span multiple levels. For convenience, if the ``section:``
    part is omitted, interpolation defaults to the current section (and possibly
-   the default values from the special section).
+   the default values from the special section). To use a bare ``$`` the user
+   can escape it by writing ``$$``.
 
    For example, the configuration specified above with basic interpolation,
    would look like this with extended interpolation:
diff -r 395904f70d6a Lib/configparser.py
--- a/Lib/configparser.py	Fri Mar 21 11:24:40 2014 -0400
+++ b/Lib/configparser.py	Fri Mar 21 08:47:31 2014 -0700
@@ -425,7 +425,8 @@
 
 class ExtendedInterpolation(Interpolation):
     """Advanced variant of interpolation, supports the syntax used by
-    `zc.buildout'. Enables interpolation between sections."""
+    `zc.buildout'. Enables interpolation between sections. A single $ can
+    be escaped by writing $$."""
 
     _KEYCRE = re.compile(r"\$\{([^}]+)\}")