I'm using Windows XP with Visual Studio 2003. I've compiled boost 1.33.1 successfully with bjam and installed the libs and DLLs into my environment. I started playing with the serialization library. I created a win32 console project and copied in the demo.cpp serialization program. It compiles and runs just fine. I then started added serialization to my own project and started running into problem after problem. I've since commented out all my own code except for the following: I copied the gps_position class directly from demo.cpp into my project. At the top of the file, I've included the following files: #include <boost/serialization/type_info_implementation.hpp> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/serialization/base_object.hpp> #include <boost/serialization/utility.hpp> In my class Manager, I wrote the following method: void Manager::save(const std::string & filename) { boost::recursive_mutex::scoped_lock lock(_nodeMutex); std::ofstream outFile; outFile.open(filename.c_str(), std::ios::binary); boost::archive::text_oarchive archiveFile(outFile); // simple test const gps_position g; archiveFile << g; outFile.close(); } Trying to compile, I get the following errors: ..\API\inc\boost\archive\detail\oserializer.hpp(131) : error C2027: use of undefined type 'boost::serialization::extended_type_info_null<T>' with [ T=gps_position ] ..\API\inc\boost\archive\detail\oserializer.hpp(131) : see reference to class template instantiation 'boost::serialization::extended_type_info_null<T>' being compiled with [ T=gps_position ] ..\API\inc\boost\archive\detail\oserializer.hpp(128) : while compiling class-template member function 'bool boost::archive::detail::oserializer<Archive,T>::is_polymorphic(void) const' with [ Archive=boost::archive::text_oarchive, T=gps_position ] ..\API\inc\boost\archive\detail\oserializer.hpp(264) : see reference to class template instantiation 'boost::archive::detail::oserializer<Archive,T>' being compiled with [ Archive=boost::archive::text_oarchive, T=gps_position ] . . . *snip* As far as my project settings, I'm compiling a win32 DLL, with the Multithread Debug C++ standard library DLL. I have exceptions and RTTI enabled. Basically the same settings I used for compiling demo.cpp. If I comment out the "archiveFile << g;" line, it compiles fine. Any help would be greatly appreciated! Thank you, Scott