You can configure the confirm dialog through a ConfirmText property that defines the confirmation text. The boolean result can be exposed in the arguments of the click event. If there is a RadWindowManager on the same page a radconfirm should be used otherwise - the browser one. For the time being the functionality can be achieved manually as illustrated in this demo - http://demos.telerik.com/aspnet-ajax/button/examples/confirm/defaultcs.aspx