<%@ Page Language="C#" %> <script runat="server"> public void DetectChange(object sender, EventArgs e) { HtmlInputCheckBox cb = (HtmlInputCheckBox) sender; Response.Write("Control <b>" + cb.UniqueID + "</b> changed<br>"); } </script> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title>Server changes</title> </head> <body> <div id="pageContent"> <form id="Form1" runat="server"> <input runat="server" type="checkbox" id="one" onserverchange="DetectChange" />One<br /> <input runat="server" type="checkbox" id="two" onserverchange="DetectChange" />Two<br /> <input runat="server" type="checkbox" id="three" onserverchange="DetectChange" />Three<br /> <input runat="server" type="submit" value="Submit" /> </form> </div> </body> </html>