Hi I'm using VS2008 and boost 1.45 I have a static library that serializes to an xml file. I have a test app that calls a method within this static library to create the XML file. The following linker problem occurs and I cannot resolve it. Can anyone assist? Error 1 error LNK2019: unresolved external symbol "public: void __thiscall BaseState::serialize<class boost::archive::xml_oarchive>(class boost::archive::xml_oarchive &,unsigned int)" (??$serialize@Vxml_oarchive@archive@boost@@@BaseState@@QAEXAAVxml_oarchive@archive@boost@@I@Z) referenced in function "public: static void __cdecl boost::serialization::access::serialize<class boost::archive::xml_oarchive,class BaseState>(class boost::archive::xml_oarchive &,class BaseState &,unsigned int)" (??$serialize@Vxml_oarchive@archive@boost@@VBaseState@@@access@serialization@boost@@SAXAAVxml_oarchive@archive@2@AAVBaseState@@I@Z) dataAPIcpp.lib TestAPI Patrick.