diff --git a/admin/configuration.php b/admin/configuration.php
index 36a2901ae..0f2e8bd34 100644
--- a/admin/configuration.php
+++ b/admin/configuration.php
@@ -246,6 +246,11 @@ switch ($page['section'])
         'CONF_GALLERY_TITLE' => htmlspecialchars($conf['gallery_title']),
         'CONF_PAGE_BANNER' => htmlspecialchars($conf['page_banner']),
         'CONF_GALLERY_URL' => $conf['gallery_url'],
+        'week_starts_on_options' => array(
+          'sunday' => $lang['day'][0],
+          'monday' => $lang['day'][1],
+          ),
+        'week_starts_on_options_selected' => $conf['week_starts_on'],
         ));
 
     foreach ($main_checkboxes as $checkbox)
diff --git a/admin/themes/default/template/configuration.tpl b/admin/themes/default/template/configuration.tpl
index 7a6583779..903255baf 100644
--- a/admin/themes/default/template/configuration.tpl
+++ b/admin/themes/default/template/configuration.tpl
@@ -87,6 +87,15 @@
         <input type="checkbox" name="email_admin_on_new_user" {if ($main.email_admin_on_new_user)}checked="checked"{/if}>
       </label>
     </li>
+
+    <li>
+      <label>
+        <span class="property">
+          {'Week starts on'|@translate}
+          {html_options name="week_starts_on" options=$main.week_starts_on_options selected=$main.week_starts_on_options_selected}
+        </span>
+      </label>
+    </li>
   </ul>
 </fieldset>
 {/if}
diff --git a/include/calendar_monthly.class.php b/include/calendar_monthly.class.php
index 1f7fdeee7..b3911ddb8 100644
--- a/include/calendar_monthly.class.php
+++ b/include/calendar_monthly.class.php
@@ -330,7 +330,7 @@ function build_year_calendar(&$tpl_var)
 
 function build_month_calendar(&$tpl_var)
 {
-  global $page;
+  global $page, $lang, $conf;
 
   $query='SELECT '.pwg_db_get_dayofmonth($this->date_field).' as period,
             COUNT(DISTINCT id) as count';
@@ -368,9 +368,12 @@ SELECT id, file,tn_ext,path, width, height, '.pwg_db_get_dayofweek($this->date_f
     $items[$day]['width'] = $row['width'];
     $items[$day]['height'] = $row['height'];
     $items[$day]['dow'] = $row['dow'];
-  }
 
-  global $lang, $conf;
+    if ('sunday' == $conf['week_starts_on'])
+    {
+      $items[$day]['dow']++;
+    }
+  }
 
   if ( !empty($items)
       and $conf['calendar_month_cell_width']>0
@@ -395,7 +398,11 @@ SELECT id, file,tn_ext,path, width, height, '.pwg_db_get_dayofweek($this->date_f
     {
       $first_day_dow -= 1;
     }
-    array_push( $wday_labels, array_shift($wday_labels) );
+
+    if ('monday' == $conf['week_starts_on'])
+    {
+      array_push( $wday_labels, array_shift($wday_labels) );
+    }
     // END - pass now in week starting Monday
 
     $cell_width = $conf['calendar_month_cell_width'];
diff --git a/install/config.sql b/install/config.sql
index f54679352..02f6f71a1 100644
--- a/install/config.sql
+++ b/install/config.sql
@@ -51,3 +51,4 @@ INSERT INTO piwigo_config (param,value,comment)
     'a:11:{s:6:"author";b:1;s:10:"created_on";b:1;s:9:"posted_on";b:1;s:10:"dimensions";b:1;s:4:"file";b:1;s:8:"filesize";b:1;s:4:"tags";b:1;s:10:"categories";b:1;s:6:"visits";b:1;s:12:"average_rate";b:1;s:13:"privacy_level";b:1;}',
     'Information displayed on picture page'
   );
+INSERT INTO piwigo_config (param,value,comment) VALUES ('week_starts_on','monday','Monday may not be the first day of the week');
diff --git a/install/db/93-database.php b/install/db/93-database.php
new file mode 100644
index 000000000..4d59aa17b
--- /dev/null
+++ b/install/db/93-database.php
@@ -0,0 +1,42 @@
+<?php
+// +-----------------------------------------------------------------------+
+// | Piwigo - a PHP based picture gallery                                  |
+// +-----------------------------------------------------------------------+
+// | Copyright(C) 2008-2010 Piwigo Team                  http://piwigo.org |
+// | Copyright(C) 2003-2008 PhpWebGallery Team    http://phpwebgallery.net |
+// | Copyright(C) 2002-2003 Pierrick LE GALL   http://le-gall.net/pierrick |
+// +-----------------------------------------------------------------------+
+// | This program is free software; you can redistribute it and/or modify  |
+// | it under the terms of the GNU General Public License as published by  |
+// | the Free Software Foundation                                          |
+// |                                                                       |
+// | This program is distributed in the hope that it will be useful, but   |
+// | WITHOUT ANY WARRANTY; without even the implied warranty of            |
+// | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU      |
+// | General Public License for more details.                              |
+// |                                                                       |
+// | You should have received a copy of the GNU General Public License     |
+// | along with this program; if not, write to the Free Software           |
+// | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, |
+// | USA.                                                                  |
+// +-----------------------------------------------------------------------+
+
+if (!defined('PHPWG_ROOT_PATH'))
+{
+  die('Hacking attempt!');
+}
+
+$upgrade_description = 'Monday may not be the first day of the week';
+
+$query = '
+INSERT INTO '.PREFIX_TABLE.'config (param,value,comment)
+  VALUES (\'week_starts_on\',\'monday\', \''.$upgrade_description.'\')
+;';
+pwg_query($query);
+
+echo
+"\n"
+. $upgrade_description
+."\n"
+;
+?>
diff --git a/language/en_UK/admin.lang.php b/language/en_UK/admin.lang.php
index 6edb53994..47bf089ee 100644
--- a/language/en_UK/admin.lang.php
+++ b/language/en_UK/admin.lang.php
@@ -799,4 +799,5 @@ $lang['Type here the title'] = 'Type here the title';
 $lang['remove creation date'] = 'remove creation date';
 $lang['with no album'] = 'with no album';
 $lang['with no tag'] = 'with no tag';
+$lang['Week starts on'] = 'Week starts on';
 ?>
diff --git a/language/fr_FR/admin.lang.php b/language/fr_FR/admin.lang.php
index f6349e204..4e49136d6 100644
--- a/language/fr_FR/admin.lang.php
+++ b/language/fr_FR/admin.lang.php
@@ -803,4 +803,5 @@ $lang['Type here the title'] = 'Entrez ici le titre';
 $lang['remove creation date'] = 'supprimer la date de création';
 $lang['with no album'] = 'sans album';
 $lang['with no tag'] = 'sans tag';
+$lang['Week starts on'] = 'La semaine commence le';
 ?>