Sometimes it is useful to be able to download extra functionality into your application at runtime. It's always been possible to make a server call from Silverlight to download an extra assembly and load it into memory. But what if you'd like to download a bunch of assemblies in neat zipped up package. As I'm sure you're already aware - this is exactly how Silverlight applications are downloaded. In a zip file called a xap.It's easy to make another XAP that contains just libraries for use later. In Visual Studio, choose Add New Project and choose Silverlight Application. Yup, that was Application, not class library. Now just delete the App.xaml and App.xaml.cs files to make it a Silverlight class library with the added benefit of being compiled and packed into a tiny xap file. You can also delete the MainWindow.xaml if you don't need it. Read more: UK Application Development Consulting