Hi We were having problems while linking boost program_options dynamically in Visual Studio.NET Linking to lib file: boost_program_options-vc71-mt-gd-1_33.lib d:\Develop\SDK and Libraries\boost_1_33_0\boost\program_options\variables_map.hpp(130) : warning C4273: 'boost::program_options::store' : inconsistent dll linkage d:\Develop\SDK and Libraries\boost_1_33_0\boost\program_options\variables_map.hpp(138) : warning C4273: 'boost::program_options::store' : inconsistent dll linkage Problem is that in file variables_map.hpp 'BOOST_PROGRAM_OPTIONS_DECL ' is missing in friend declaration of function 'store'. so: ======================= class BOOST_PROGRAM_OPTIONS_DECL variables_map : public abstract_variables_map, public std::map { ... friend void store(...); }; ... BOOST_PROGRAM_OPTIONS_DECL void store(...); ======================= should be: ======================= class BOOST_PROGRAM_OPTIONS_DECL variables_map : public abstract_variables_map, public std::map { ... friend void BOOST_PROGRAM_OPTIONS_DECL store(...); }; ... BOOST_PROGRAM_OPTIONS_DECL void store(...); =======================