With the following line in my Microsoft Vc7 program: std::cout << to_simple_string(d) << std::endl; I get the following linker errors: error LNK2005: "public: __thiscall std::locale::id::id(unsigned int)" (??0id@locale@std@@QAE@I@Z) already defined in stdafx.obj error LNK2005: "private: __thiscall type_info::type_info(class type_info const &)" (??0type_info@@AAE@ABV0@@Z) already defined in LIBCD.lib(typinfo.obj) error LNK2005: "private: class type_info & __thiscall type_info::operator=(class type_info const &)" (?? 4type_info@@AAEAAV0@ABV0@@Z) already defined in LIBCD.lib(typinfo.obj) Clearly I am missing something important! I did put #define DATE_TIME_INLINE in my stdafx.h file and that allowed me to create dates (date d(...)) but clearly something else is needed (for IO related stuff?)... Do I have to for instance recreate the libboost_date_time.lib file with different settings? I just used 'bjam "-sTOOLS=vc7" "- sBUILD=debug release"'. Any help appreciated. Thanks to Jeff Garland and the rest of the Boost group for creating this library - I would really like to use it in my programs from now on but why won't the silly linker oblige!