Index: Doc/library/os.rst
===================================================================
--- Doc/library/os.rst  (revision 84639)
+++ Doc/library/os.rst  (working copy)
@@ -244,12 +244,12 @@
 .. function:: getlogin()
 
    Return the name of the user logged in on the controlling terminal of the
-   process.  For most purposes, it is more useful to use the environment variable
-   :envvar:`LOGNAME` to find out who the user is, or
+   process.  For most purposes, it is more useful to use the environment variables
+   :envvar:`LOGNAME` or :envvar:`USERNAME` to find out who the user is, or
    ``pwd.getpwuid(os.getuid())[0]`` to get the login name of the currently
    effective user id.
 
-   Availability: Unix.
+   Availability: Unix, Windows.
 
 
 .. function:: getpgid(pid)
Index: Lib/test/test_os.py
===================================================================
--- Lib/test/test_os.py (revision 84639)
+++ Lib/test/test_os.py (working copy)
@@ -1194,6 +1194,21 @@
         self.assertEqual(int(stdout), os.getpid())
 
 
+class LoginTests(unittest.TestCase):
+    @unittest.skipUnless(hasattr(os, 'getlogin'), "test needs os.getlogin")
+    def test_getlogin(self):
+        user_name = os.getlogin()
+        self.assertNotEqual(len(user_name), 0)
+
+        lname = os.getenv('LOGNAME')
+        if lname is not None:
+            self.assertEqual(lname, user_name)
+
+        uname = os.getenv('USERNAME')
+        if uname is not None:
+            self.assertEqual(uname, user_name)
+
+
 def test_main():
     support.run_unittest(
         FileTests,
@@ -1212,6 +1227,7 @@
         Win32SymlinkTests,
         FSEncodingTests,
         PidTests,
+        LoginTests,
     )
 
 if __name__ == "__main__":
Index: Modules/posixmodule.c
===================================================================
--- Modules/posixmodule.c       (revision 84639)
+++ Modules/posixmodule.c       (working copy)
@@ -122,6 +122,7 @@
 #ifdef _MSC_VER         /* Microsoft compiler */
 #define HAVE_GETCWD     1
 #define HAVE_GETPPID    1
+#define HAVE_GETLOGIN   1 
 #define HAVE_SPAWNV     1
 #define HAVE_EXECV      1
 #define HAVE_PIPE       1
@@ -4426,6 +4427,12 @@
 
 
 #ifdef HAVE_GETLOGIN
+
+#ifdef MS_WINDOWS
+/* for UNLEN */
+#include <lmcons.h>
+#endif
+
 PyDoc_STRVAR(posix_getlogin__doc__,
 "getlogin() -> string\n\n\
 Return the actual login name.");
@@ -4434,6 +4441,17 @@
 posix_getlogin(PyObject *self, PyObject *noargs)
 {
     PyObject *result = NULL;
+#ifdef MS_WINDOWS    
+    wchar_t user_name[UNLEN + 1];
+    DWORD nChars = _countof(user_name);
+
+    if (GetUserNameW(user_name, &nChars)) {
+        /* nChars is the number of unicode chars plus null terminator */
+        result = PyUnicode_FromWideChar(user_name, nChars - 1);
+    } 
+    else 
+        result = PyErr_SetFromWindowsErr(GetLastError());
+#else
     char *name;
     int old_errno = errno;
 
@@ -4448,10 +4466,10 @@
     else
         result = PyUnicode_DecodeFSDefault(name);
     errno = old_errno;
-
+#endif
     return result;
 }
-#endif
+#endif /* HAVE_GETLOGIN */
 
 #ifdef HAVE_GETUID
 PyDoc_STRVAR(posix_getuid__doc__,