diff --git a/docs/ref/models/fields.txt b/docs/ref/models/fields.txt
index 7300f4d..d68279c 100644
--- a/docs/ref/models/fields.txt
+++ b/docs/ref/models/fields.txt
@@ -413,6 +413,11 @@ The admin represents this as an ``<input type="text">`` with a JavaScript
 calendar, and a shortcut for "Today".  The JavaScript calendar will always
 start the week on a Sunday.
 
+.. note::
+  As currently implemented, setting ``auto_now`` or ``auto_add_now`` to
+  ``True`` will cause the field to have ``editable=False`` and ``blank=True``
+  set.
+
 ``DateTimeField``
 -----------------