XmlSerializer Element Names

I want to deserialize a class hierarchy from XML using XmlSerializer. class Base class Derived1:Base class Derived2:Base I use XMLInclude attributes on Base, and also provide the derived Types to the XmlSerializer constructor. Now my problem is that when I write the actual XML, it has to look like this: ... I'd rather be able to do ... but this causes XmlSerializer to throw exceptions saying that Derived1 was unexpected. Does anyone know how to make XmlSerializer accept this?