Hi Vicente and others, Thank you for the replies. When I took a look at codes under "thread', I found there are some places where BOOST_NO_ANSI_APIS is related ( for example in once.hpp ) #ifdef BOOST_NO_ANSI_APIS typedef wchar_t once_char_type #else typedef char once_char_type #endif I am wondering if the boost_thread is NOT related to Unicode ( some said so??? ), why are there some codes above?? My basic question is How to build Unicode version of the library ( boost_thread...1-47)? just defining BOOST_NO_ANSI_APIS in file is enough??? P.S. Our application is windows Unicode based application that needs to use all Unicode versions of libraries including boost_thread...library Thanks Yan ----------------------------------------------------- There is no relation between both librairies that I'm aware of. If you are more explicit with the problem you have, maybe we can help you better. Best, Vicente