I’ve a case where I have an ASP.NET calendar that has a page load method that automatically select a date when it’s loaded. I also have an event defined for Selected_Changed which will be triggered only when the user select any other date other than pre-selected date on the load

Private Sub ctlCalendar_SelectionChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ctlCalendar.SelectionChanged
        If (Not String.IsNullOrEmpty(CalendarPreviousPage)) Then
            BaseCalendar.SelectedDate = ctlCalendar.SelectedDate
            Response.Redirect(CalendarPreviousPage)
        End If
    End Sub

But how do I wire up an event or when the selecteddate being clicked?You can use DayRender event and attach it to a javascript in this case I want to go back to previous page. BaseCalendar.Selected date can be any date where you want to set up/wire up the logic

 Private Sub ctlCalendar_DayRender(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.DayRenderEventArgs) Handles ctlCalendar.DayRender
        Dim d As CalendarDay
        Dim c As TableCell
        d = e.Day
        c = e.Cell

        If (BaseCalendar.SelectedDate.Value = d.Date) Then
            c.Attributes.Add("OnClick", "history.go(-1)")
        End If

    End Sub