.master.cs: protected void Page_Load(object sender, EventArgs e) { switch (CurrentPage) { case PageList.Home: DefaultLink.Attributes["class"] = "active"; break; case PageList.Clients: ClientsLink.Attributes["class"] = "active"; break; case PageList.Contact: ContactLink.Attributes["class"] = "active"; break; case PageList.Services: ServicesLink.Attributes["class"] = "active"; break; case PageList.Telephony: TelephonyLink.Attributes["class"] = "active"; break; case PageList.Websites: WebsitesLink.Attributes["class"] = "active"; break; case PageList.HomeAutomation: HomeAutomationLink.Attributes["class"] = "active"; break; } } .master: <%@ Master Language="C#" AutoEventWireup="true" Inherits="MaccaSoft.Web.MasterPage" CodeFile="~/MasterPage.master.cs" %>