I wanted to start a list of common reasons why Silverlight Serializer throws the MissingMethodException exception. First off you need to make sure you've got a WP7 build of the Silverlight Serializer - you can get a copy from the WP7Contrib code base if you don't want to build your own. Classes causing MissingMethodException exception: System.Uri, System.Globalization.CultureInfo To correct the issue for the above classes you will have to implement a classes that acts a serialization proxy, the one shown below is for System.Uri. [Serializer(typeof(Uri))] public sealed class SerializeUri : ISerializeObject { public object[] Serialize(object target) { return new object[] { ((Uri) target).ToString() }; } public object Deserialize(object[] data) { retu...