I’ve been battling this literally for months. I couldn’t seem to get .svc files hosted on my Vista machine. It wasn’t until tonight that I really needed to get it working. It took me the better part of an hour to find Guy Burstein’s WCF on IIS7 on Vista - Adding .svc Handler post (no idea why this wasn’t ranking higher on Google). If you’re seeing this: Server Error in Application “Default Web Site/...” HTTP Error 404.3 - Not Found Then do the following: ...