diff -r eac4e23ce2fd Modules/_localemodule.c
--- a/Modules/_localemodule.c	Sat Apr 13 15:29:22 2013 -0400
+++ b/Modules/_localemodule.c	Sat Apr 13 15:33:36 2013 -0400
@@ -312,11 +312,28 @@
 }
 #endif
 
+#ifdef HAVE_NL_TIME_FIRST_WEEKDAY
+static const char *
+handle_nl_time_week_1stday(const char *result)
+{
+    const unsigned long week_1stday = (const unsigned long)result;
+    switch (week_1stday) {
+    case 19971130:  /* Sunday */
+        return "6";
+    case 19971201:  /* Monday */
+        return "1";
+    default:        /* St Swithin's Day */
+        return "";
+    }
+}
+#endif
+
 #ifdef HAVE_LANGINFO_H
-#define LANGINFO(X) {#X, X}
+#define LANGINFO(X) {#X, X, NULL}
 static struct langinfo_constant{
     char* name;
     int value;
+    const char* (*interp)(const char *result);
 } langinfo_constants[] =
 {
     /* These constants should exist on any langinfo implementation */
@@ -414,6 +431,12 @@
 #ifdef NOEXPR
     LANGINFO(NOEXPR),
 #endif
+#ifdef HAVE_NL_TIME_FIRST_WEEKDAY
+    /* Only glibc appears to provide this functionality */
+    /*  can't use LANGINFO since they start with _ */
+    { "TIME_FIRST_WEEKDAY", _NL_TIME_FIRST_WEEKDAY, NULL },
+    { "TIME_WEEK_1STDAY", _NL_TIME_WEEK_1STDAY, handle_nl_time_week_1stday },
+#endif
 #ifdef _DATE_FMT
     /* This is not available in all glibc versions that have CODESET. */
     LANGINFO(_DATE_FMT),
@@ -440,6 +463,8 @@
                instead of an empty string for nl_langinfo(ERA).  */
             const char *result = nl_langinfo(item);
             result = result != NULL ? result : "";
+            if (langinfo_constants[i].interp)
+                result = langinfo_constants[i].interp(result);
             return PyUnicode_DecodeLocale(result, NULL);
         }
     PyErr_SetString(PyExc_ValueError, "unsupported langinfo constant");
@@ -447,6 +472,42 @@
 }
 #endif /* HAVE_LANGINFO_H */
 
+/* hide complexity of langinfo.h and TIME_FIRST_WEEKDAY/TIME_WEEK_1STDAY */
+/* returns locale dependent values for Calendar module */
+static PyObject*
+PyLocale_firstdayofweek(PyObject* self)
+{
+    int start;
+#ifdef HAVE_NL_TIME_FIRST_WEEKDAY
+    int first_weekday = nl_langinfo(_NL_TIME_FIRST_WEEKDAY)[0];
+    long week_1stday = (long)nl_langinfo(_NL_TIME_WEEK_1STDAY);
+    switch (week_1stday) {
+    default:
+    case 19971130:
+        week_1stday = 0;
+        break;
+    case 19971201:
+        week_1stday = 1;
+        break;
+    }
+    /* should be 0 for Sunday or 1 for Monday, clamp to
+     * Calendar.firstdayofweek values
+     */
+    start = (week_1stday + first_weekday - 1) % 7;
+    if (start == 0)
+        start = 6;
+    else
+        start = 0;
+#else
+    start = 0;
+#endif
+    return Py_BuildValue("i", start);
+}
+
+PyDoc_STRVAR(firstdayofweek__doc__,
+"firstdayofweek() -> integer\n"
+"Return a best guess at the first day of the week, 0 == Monday, 6 == Sunday");
+
 #ifdef HAVE_LIBINTL_H
 
 PyDoc_STRVAR(gettext__doc__,
@@ -581,6 +642,8 @@
   {"nl_langinfo", (PyCFunction) PyLocale_nl_langinfo,
    METH_VARARGS, nl_langinfo__doc__},
 #endif
+  {"firstdayofweek", (PyCFunction) PyLocale_firstdayofweek,
+   METH_NOARGS, firstdayofweek__doc__},
 #ifdef HAVE_LIBINTL_H
   {"gettext",(PyCFunction)PyIntl_gettext,METH_VARARGS,
     gettext__doc__},
diff -r eac4e23ce2fd configure.ac
--- a/configure.ac	Sat Apr 13 15:29:22 2013 -0400
+++ b/configure.ac	Sat Apr 13 15:33:36 2013 -0400
@@ -4250,6 +4250,20 @@
   [Define if you have struct stat.st_mtimensec])
 fi
 
+# checking for glibc extensions to langinfo.h
+#  _NL_TIME_FIRST_WEEKDAY isn't #define'd, so test it directly
+AC_MSG_CHECKING(for _NL_TIME_FIRST_WEEKDAY)
+AC_CACHE_VAL(ac_cv_have_nl_time_first_weekday,
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <langinfo.h>]], [[
+int main(int argc, char *argv[]) { return !!nl_langinfo(_NL_TIME_FIRST_WEEKDAY); }]])],
+  [ac_cv_have_nl_time_first_weekday=yes],[ac_cv_have_nl_time_first_weekday=no]))
+AC_MSG_RESULT($ac_cv_have_nl_time_first_weekday)
+if test "$ac_cv_have_nl_time_first_weekday" = yes
+then
+  AC_DEFINE(HAVE_NL_TIME_FIRST_WEEKDAY, 1,
+  [Define if you have _NL_TIME_FIRST_WEEKDAY in langinfo.h])
+fi
+
 ac_save_cppflags="$CPPFLAGS"
 CPPFLAGS="$CPPFLAGS -I/usr/include/ncursesw"
 # On HP/UX 11.0, mvwdelch is a block with a return statement