Hi, I use Visual Studios 2005. In my project file, I include the library in linker: "Additional Library Directories: ..\..\boost\lib" I have these libs in the boost\lib directory: libboost_date_time-vc80-mt-1_33_1.lib libboost_date_time-vc80-mt-gd-1_33_1.lib libboost_regex-vc80-mt-1_33_1.lib libboost_regex-vc80-mt-gd-1_33_1.lib libboost_thread-vc80-mt-1_33_1.lib libboost_thread-vc80-mt-gd-1_33_1.lib When I build my project as a debug build. it compiles fine. However, if I change to release build, it gives me this error: Error 1 fatal error LNK1104: cannot open file 'libboost_regex-vc80-mt-s-1_33_1.lib' Please let me know what I need to do to have it point to "libboost_regex-vc80-mt-1_33_1.lib" instead of "libboost_regex-vc80-mt-s-1_33_1.lib". Thanks very much, Maggie