Having worked so much with BizTalk, haven't had the chance to create a pure .NET 2.0 web service (automaticly generated WSDL). Much to my surprise, the concept of a "Required Field" is not explicitly supported -- i.e. setting minOccurs = 1, etc. For future reference, some mitigating suggestions are provided by Microsoft here: http://msdn2.microsoft.com/en-us/library/zds0b35c.aspx. Feels like going back to the stone ages. Apparently this is much better with WCF bindings....