You can either a buy a 3rd party control or write your own to get this working. And I was brave enough to write my own, so here is what I did. The ASP.NET calendar control fires an event when you click on a day (DayRender ). Add a handler to this event weeklyCalendar1.DayRender += new DayRenderEventHandler(weekl... in the Event Handler add the following code: void weeklyCalendar1_DayRender(o... sender, DayRenderEventArgs e) { if (e.Day.Date > DateTime.Today) { // e.Cell.BackColor ......