//string of the requestor's URL string cookieName = FormsAuthentication.GetRedirectUrl( txtUserName.Text, false ).Trim(); //start position of my cookie name int startCookie = cookieName.LastIndexOf( "/" ) + 1; //ending position of my cookie name int cookieLength = cookieName.LastIndexOf( "." ) - startCookie; //parse the redirect URL to get a dynamic cookie name cookieName = "." + cookieName.Substring( startCookie, cookieLength ) + "Auth"; //get the cookie HttpCookie cookie = FormsAuthentication.GetAuthCookie( txtUserName.Text, false ); //give it my new name cookie.Name = cookieName; //add it to the response object Response.Cookies.Add( cookie ); //navigate back to the original requestor Response.Redirect( FormsAuthentication.GetRedirectUrl( txtUserName.Text, false ) );I don't know how much I like this, mainly because the forms element's name attribute (in the web.config of the protected app) must be equal to "." + the defualt start page + "Auth" (in this case ".PHYSCNTAuth"). I don't know if I like putting a "Have to do it this way" in there, but oh well.