diff --git a/Lib/datetime.py b/Lib/datetime.py
--- a/Lib/datetime.py
+++ b/Lib/datetime.py
@@ -1434,6 +1434,15 @@
                                   self.hour, self.minute, self.second,
                                   dst)
 
+    def timestamp(self):
+        "Return POSIX timestamp as float"
+        if self._tzinfo is None:
+            return _time.mktime((self.year, self.month, self.day,
+                                 self.hour, self.minute, self.second,
+                                 -1, -1, -1)) + self.microsecond / 1e6
+        else:
+            return (self - _EPOCH).total_seconds()
+
     def utctimetuple(self):
         "Return UTC time tuple compatible with time.gmtime()."
         offset = self.utcoffset()
@@ -1889,7 +1898,7 @@
 timezone.utc = timezone._create(timedelta(0))
 timezone.min = timezone._create(timezone._minoffset)
 timezone.max = timezone._create(timezone._maxoffset)
-
+_EPOCH = datetime(1970, 1, 1, tzinfo=timezone.utc)
 """
 Some time zone algebra.  For a datetime x, let
     x.n = x stripped of its timezone -- its naive time.
diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
--- a/Lib/test/datetimetester.py
+++ b/Lib/test/datetimetester.py
@@ -1735,6 +1735,21 @@
         got = self.theclass.utcfromtimestamp(ts)
         self.verify_field_equality(expected, got)
 
+    @support.run_with_tz('EST+05EDT,M4.1.0,M10.5.0')
+    def test_timestamp_naive(self):
+        t = datetime(1970, 1, 1)
+        self.assertEqual(t.timestamp(), 18000.0)
+        t = datetime(1970, 1, 1, 1, 2, 3, 4)
+        self.assertEqual(t.timestamp(),
+                         18000.0 + 3600 + 2*60 + 3 + 4*1e-6)
+
+    def test_timestamp_aware(self):
+        t = datetime(1970, 1, 1, tzinfo=timezone.utc)
+        self.assertEqual(t.timestamp(), 0.0)
+        t = datetime(1970, 1, 1, 1, 2, 3, 4, tzinfo=timezone.utc)
+        self.assertEqual(t.timestamp(),
+                         3600 + 2*60 + 3 + 4*1e-6)
+
     def test_microsecond_rounding(self):
         for fts in [self.theclass.fromtimestamp,
                     self.theclass.utcfromtimestamp]:
diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
--- a/Modules/_datetimemodule.c
+++ b/Modules/_datetimemodule.c
@@ -766,6 +766,8 @@
 
 /* The interned UTC timezone instance */
 static PyObject *PyDateTime_TimeZone_UTC;
+/* The interned Epoch datetime instance */
+static PyObject *PyDateTime_Epoch;
 
 /* Create new timezone instance checking offset range.  This
    function does not check the name argument.  Caller must assure
@@ -4748,6 +4750,39 @@
 }
 
 static PyObject *
+datetime_timestamp(PyDateTime_DateTime *self)
+{
+    PyObject *result;
+
+    if (HASTZINFO(self) && self->tzinfo != Py_None) {
+        PyObject *delta;
+        delta = datetime_subtract((PyObject *)self, PyDateTime_Epoch);
+        if (delta == NULL)
+            return NULL;
+        result = delta_total_seconds(delta);
+        Py_DECREF(delta);
+    }
+    else {
+        struct tm time;
+        double timestamp;
+        memset((void *) &time, '\0', sizeof(struct tm));
+        time.tm_year = GET_YEAR(self) - 1900;
+        time.tm_mon = GET_MONTH(self) - 1;
+        time.tm_mday = GET_DAY(self);
+        time.tm_hour = DATE_GET_HOUR(self);
+        time.tm_min = DATE_GET_MINUTE(self);
+        time.tm_sec = DATE_GET_SECOND(self);
+        time.tm_wday = -1;
+        time.tm_yday = -1;
+        time.tm_isdst = -1;
+        timestamp = mktime(&time);
+        timestamp += DATE_GET_MICROSECOND(self) / 1e6;
+        result = PyFloat_FromDouble(timestamp);
+    }
+    return result;
+}
+
+static PyObject *
 datetime_getdate(PyDateTime_DateTime *self)
 {
     return new_date(GET_YEAR(self),
@@ -4894,6 +4929,9 @@
     {"timetuple",   (PyCFunction)datetime_timetuple, METH_NOARGS,
      PyDoc_STR("Return time tuple, compatible with time.localtime().")},
 
+    {"timestamp",   (PyCFunction)datetime_timestamp, METH_NOARGS,
+     PyDoc_STR("Return POSIX timestamp.")},
+
     {"utctimetuple",   (PyCFunction)datetime_utctimetuple, METH_NOARGS,
      PyDoc_STR("Return UTC time tuple, compatible with time.localtime().")},
 
@@ -5151,6 +5189,12 @@
         return NULL;
     Py_DECREF(x);
 
+    /* Epoch */
+    PyDateTime_Epoch = new_datetime(1970, 1, 1, 0, 0, 0, 0,
+				    PyDateTime_TimeZone_UTC);
+    if (PyDateTime_Epoch == NULL)
+      return NULL;
+
     /* module initialization */
     PyModule_AddIntConstant(m, "MINYEAR", MINYEAR);
     PyModule_AddIntConstant(m, "MAXYEAR", MAXYEAR);