I need to build boost regex library with ICU support. I followed instruction in: http://www.boost.org/doc/libs/1_46_1/libs/regex/doc/html/boost_regex/install... First I downloaded ICU library and compiled it without any problem. Then I ran the following command: cd /opt/third_party_libraries/boost_1_46_1/libs/regex/build/ (Boost source code is in "/opt/third_party_libraries/boost_1_46_1") [root@pli-dc-build build]# /opt/third_party_libraries/boost_1_46_1/bjam include=/usr/local/ --toolset=gcc install Performing configuration checks - has_icu builds : yes ...patience... ... ... gcc.compile.c++ ../../../bin.v2/libs/regex/build/gcc-3.4.6/debug/usinstances.o gcc.link.dll ../../../bin.v2/libs/regex/build/gcc-3.4.6/debug/libboost_regex.so.1.46.1 common.copy /opt/third_party_libraries/boost_1_46_1/lib/libboost_regex.so.1.46.1 ln-UNIX /opt/third_party_libraries/boost_1_46_1/lib/libboost_regex.so ln-UNIX /opt/third_party_libraries/boost_1_46_1/lib/libboost_regex.so.1 ln-UNIX /opt/third_party_libraries/boost_1_46_1/lib/libboost_regex.so.1.46 ...updated 22 targets... The build process is successful and I can find the library in "/opt/third_party_libraries/boost_1_46_1/lib/libboost_regex.so.1.46.1". The question is: does this library support multiple threads? I did some research on this topic, it seems like even though the name does not contain "mt", it is actually thread safe. Or do I have to pass extra parameter to generate thread safe version? The normal boost build process generates regex library with name like: libboost_regex-gcc34-mt-1_46_1.so.1.46.1 (http://www.boost.org/doc/libs/1_46_1/more/getting_started/unix-variants.html) From the name, I know if the library supports multiple threads. My development box: uname -a Linux 2.6.18-308.1.1.el5PAE #1 SMP Wed Mar 7 04:57:46 EST 2012 i686 i686 i386 GNU/Linux gcc --version gcc (GCC) 3.4.6 20060404 (Red Hat 3.4.6-4.1) Copyright (C) 2006 Free Software Foundation, Inc. Thanks