If your Silverlight app references services, the endpoints to these services are stored within a config file within the xap bundle - which is usually deployed as .xap file within the ClientBin dir of your web app. To change the end point urls:1) Rename the xap file (eg within E:\Demos\MySilverlightApp.W... to .zip. 2) Unzip it 3) Edit the ServiceReferences.ClientConfig file (to update the endpoint url) and save it.4) Recreate the zip file5) Rename the .zip file as .xap That's it...