Hello, When trying to serialize a STL map, doing the following (in Visual C++ 7.1): class Being { private: std::wstring Name, Description; friend class boost::serialization::access; public: template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & this->Name; ar & this->Description; } }; class Ecosystem { private: friend class boost::serialization::access; std::mapstd::wstring,Being Beings; public: template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & this->Beings; } }; ... ar & ecosystem; // Making the serialization within some function (storing) ... I get this compile-time error: "c:\Boost\include\boost-1_33_1\boost\serialization\access.hpp(109): error C2039: 'serialize' : is not a member of 'std::map<_Kty,_Ty>' with [_Kty=std::wstring,_Ty=Models::Beings]" Has anyone any ideas about the reason for this error? Thanking you in advance, David