Index: django/newforms/extras/widgets.py
===================================================================
--- django/newforms/extras/widgets.py	(revision 7141)
+++ django/newforms/extras/widgets.py	(working copy)
@@ -3,6 +3,7 @@
 """
 
 import datetime
+import re
 
 from django.newforms.widgets import Widget, Select
 from django.utils.dates import MONTHS
@@ -10,6 +11,8 @@
 
 __all__ = ('SelectDateWidget',)
 
+RE_DATE = re.compile(r'(\d{4})-(\d\d?)-(\d\d?)$')
+
 class SelectDateWidget(Widget):
     """
     A Widget that splits date input into three <select> boxes.
@@ -32,10 +35,13 @@
 
     def render(self, name, value, attrs=None):
         try:
-            value = datetime.date(*map(int, value.split('-')))
             year_val, month_val, day_val = value.year, value.month, value.day
-        except (AttributeError, TypeError, ValueError):
+        except AttributeError:
             year_val = month_val = day_val = None
+            if isinstance(value, basestring):
+                match = RE_DATE.match(value)
+                if match:
+                    year_val, month_val, day_val = [int(v) for v in match.groups()]
 
         output = []
 
Index: tests/regressiontests/forms/extra.py
===================================================================
--- tests/regressiontests/forms/extra.py	(revision 7141)
+++ tests/regressiontests/forms/extra.py	(working copy)
@@ -144,6 +144,73 @@
 <option value="2016">2016</option>
 </select>
 
+Accepts a datetime or a string:
+
+>>> w.render('mydate', datetime.date(2010, 4, 15)) == w.render('mydate', '2010-04-15')
+True
+
+Invalid dates still render the failed date:
+>>> print w.render('mydate', '2010-02-31')
+<select name="mydate_month">
+<option value="1">January</option>
+<option value="2" selected="selected">February</option>
+<option value="3">March</option>
+<option value="4">April</option>
+<option value="5">May</option>
+<option value="6">June</option>
+<option value="7">July</option>
+<option value="8">August</option>
+<option value="9">September</option>
+<option value="10">October</option>
+<option value="11">November</option>
+<option value="12">December</option>
+</select>
+<select name="mydate_day">
+<option value="1">1</option>
+<option value="2">2</option>
+<option value="3">3</option>
+<option value="4">4</option>
+<option value="5">5</option>
+<option value="6">6</option>
+<option value="7">7</option>
+<option value="8">8</option>
+<option value="9">9</option>
+<option value="10">10</option>
+<option value="11">11</option>
+<option value="12">12</option>
+<option value="13">13</option>
+<option value="14">14</option>
+<option value="15">15</option>
+<option value="16">16</option>
+<option value="17">17</option>
+<option value="18">18</option>
+<option value="19">19</option>
+<option value="20">20</option>
+<option value="21">21</option>
+<option value="22">22</option>
+<option value="23">23</option>
+<option value="24">24</option>
+<option value="25">25</option>
+<option value="26">26</option>
+<option value="27">27</option>
+<option value="28">28</option>
+<option value="29">29</option>
+<option value="30">30</option>
+<option value="31" selected="selected">31</option>
+</select>
+<select name="mydate_year">
+<option value="2007">2007</option>
+<option value="2008">2008</option>
+<option value="2009">2009</option>
+<option value="2010" selected="selected">2010</option>
+<option value="2011">2011</option>
+<option value="2012">2012</option>
+<option value="2013">2013</option>
+<option value="2014">2014</option>
+<option value="2015">2015</option>
+<option value="2016">2016</option>
+</select>
+
 Using a SelectDateWidget in a form:
 
 >>> class GetDate(Form):
