Hi there, Consider a hierarchy of classes that is accessed through an abstract base class. The most derived class is a template which is "filled" with the basic types bool, char, boost::int32_t and double. I use typedefs of the kind "typedef GParameterT<char> GChar;" for ease of use. This is held in its own header file, in this case GChar.hpp . A corresponding GChar.cpp holds the export statement needed to register the class (or typedef in this case): #include <boost/serialization/export.hpp> BOOST_CLASS_EXPORT(Gem::GenEvA::GChar) There are also identical (except for base types) files for GDouble, GBoolean and GInt32 (holding the tell-tale typedefs and exports for the corresponding types). I'm using unit tests for my library, and there you will find code like: // Test (de-)serialization in different modes { // plain text format T gpt4(gpt0); BOOST_CHECK(gpt4.isEqualTo(gpt0)); BOOST_CHECK_NO_THROW(gpt4.fromString(gpt1.toString(TEXTSERIALIZATION), TEXTSERIALIZATION)); BOOST_CHECK(!gpt4.isEqualTo(gpt0)); BOOST_CHECK(gpt4.isSimilarTo(gpt1, exp(-10))); } // [ ... further serialization modes removed ... ] T can again be GChar, GBoolean, GDouble or GInt32 . to/fromString is a simple wrapper to the serialization calls (all happening through the base pointer). Now I have the problem that the toString/fromString throws an "unregistered class" with Boost 1.4.1, but **only** if GParameterT is fed a double or a boost::int32_t . (De-)Serialization works fine with char and bool as template parameter. With Boost 1.38, no errors occur at all, and also my production code works nicely with 1.41 (and it uses Boost.Serialization extensively). Any idea ? In any case: Thanks for a great library and have a nice christmas time and a happy new year! Best Regards, Ruediger