Index: Lib/ConfigParser.py
===================================================================
--- Lib/ConfigParser.py	(revision 60566)
+++ Lib/ConfigParser.py	(working copy)
@@ -511,12 +511,13 @@
     def get(self, section, option, raw=False, vars=None):
         """Get an option value for a given section.
 
-        All % interpolations are expanded in the return values, based on the
-        defaults passed into the constructor, unless the optional argument
-        `raw' is true.  Additional substitutions may be provided using the
-        `vars' argument, which must be a dictionary whose contents overrides
-        any pre-existing defaults.
+        If `vars' is provided, it must be a dictionary. The option is looked
+        up in `vars' (if provided), `section', and in `defaults' in that
+        order. 
 
+        All % interpolations are expanded in the return values, unless the
+        optional argument `raw' is true.
+
         The section DEFAULT is special.
         """
         d = self._defaults.copy()
Index: Doc/library/configparser.rst
===================================================================
--- Doc/library/configparser.rst	(revision 60566)
+++ Doc/library/configparser.rst	(working copy)
@@ -32,7 +32,7 @@
 :rfc:`822`; ``name=value`` is also accepted.  Note that leading whitespace is
 removed from values. The optional values can contain format strings which refer
 to other values in the same section, or values in a special ``DEFAULT`` section.
-Additional defaults can be provided on initialization and retrieval.  Lines
+Additional defaults can be provided on initialization.  Lines
 beginning with ``'#'`` or ``';'`` are ignored and may be used to provide
 comments.
 
@@ -46,8 +46,7 @@
 All reference expansions are done on demand.
 
 Default values can be specified by passing them into the :class:`ConfigParser`
-constructor as a dictionary.  Additional defaults  may be passed into the
-:meth:`get` method which will override all others.
+constructor as a dictionary.
 
 Sections are normally stored in a builtin dictionary. An alternative dictionary
 type can be passed to the :class:`ConfigParser` constructor. For example, if a
@@ -328,11 +327,12 @@
 
 .. method:: ConfigParser.get(section, option[, raw[, vars]])
 
-   Get an *option* value for the named *section*.  All the ``'%'`` interpolations
-   are expanded in the return values, based on the defaults passed into the
-   constructor, as well as the options *vars* provided, unless the *raw* argument
-   is true.
+   Get an *option* value for the named *section*. If *vars* is provided, it
+   must be a dictionary. The *option* is looked up in *vars* (if provided),
+   *section*, and in *defaults* in that order. 
 
+   All the ``'%'`` interpolations are expanded in the return values, unless
+   the optional argument `raw' is true.
 
 .. method:: ConfigParser.items(section[, raw[, vars]])