I'm having problems building programs with program_options and vc8/2005. I'm getting linker errors... any suggestions? I suspect I'm doing something obvious wrong. Linking against 1.33.1, I have $(BOOST_ROOT)\bin\boost\libs in "Additional Library directories". I get "already defined" and "unresolved" errors when I try to use program_options code that builds in vc71. For example: //no problem here... #include <boost/program_options.hpp> using namespace std; using namespace boost; using namespace boost::program_options; void func() { //but with this I get linker errors variables_map l_vm; } //...such as: 1>libboost_program_options-vc80-mt-gd-1_33_1.lib(variables_map.obj) : error LNK2005: "class std::basic_ostream<char,struct std::char_traits<char> > & __cdecl std::operator<<<char,struct std::char_traits<char>,class std::allocator<char> >(class std::basic_ostream<char,struct std::char_traits<char> > &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (??$?6DU?$char_traits@D@std@@V?$allocator@D@1@@std@@YAAAV?$basic_ostream@DU?$char_traits@D@std@@@0@AAV10@ABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@0@@Z) already defined in msvcprtd.lib(MSVCP80D.dll) //and: 1>libboost_program_options-vc80-mt-gd-1_33_1.lib(options_description.obj) : error LNK2019: unresolved external symbol "__declspec(dllimport) public: class std::reverse_iterator<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::const_iterator> __thiscall std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::rbegin(void)const " (__imp_?rbegin@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QBE?AV?$reverse_iterator@Vconst_iterator@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@2@XZ) referenced in function "public: bool __thiscall boost::program_options::option_description::match(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &,bool)const " (?match@option_description@program_options@boost@@QBE_NABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@_N@Z) Any suggestions?