Hi Naveen, First of all, if you compile your project in VS 2003, it will use the .NET 1.1 runtime. You can also make it support the 1.0 runtime through your project properties in VS.NET. "Modifying this property causes the project system to update the web.config file in your project by adding assembly binding ( and ) tags in a section. Web pages in Visual Studio-built ASP.NET Web applications are precompiled to a .dll file with a dependency on the runtime associated with the compiler." I guess setting that option in the ASP.NET tab, will compile the aspx pages on runtime to one supporting the 2.0 runtime (but not the pre compiled files, since that option was set in VS.NET) So if you would compile your project in VS.NET 2005, it will use the .NET 2.0 runtime. Gidon