Imports wc = System.Web.UI.WebControls

....

    Private Sub ButtonHandler(ByVal sender As System.Object, _
				ByVal e As System.EventArgs) Handles _
				  Button1.Click _
				, Button2.Click _
				, Button3.Click

        Dim btn As wc.Button = CType(sender, wc.Button)
        Select Case True
            Case btn Is Button1 : Label1.Text = "Button #1"
            Case btn Is Button2 : Label1.Text = "Button #2"
            Case btn Is Button3 : Label1.Text = "Button #3"
            Case Else : Label1.Text = "None of the above"
        End Select
    End Sub