[Please ignore exemplar in previous missive. I can't seem to cancel it.] Apologies in advance if this belongs on the boost-users@lists.boost.org list. After my posting vast quantities of [probably worthless] example output on jamboost@yahoogroups.com, Vladimir Prus provided [I added the -Is] this example and suggested I post it here where the Boost.config maintainers might be able to help. OS is Fedora3 on x86. We have empirically confirmed the cross-compiler being used supports pthreads. ALL the rest of the boost libs compiled successfully (with only the occasional warning). I'm only 13 targets from home. <exemplar apologies=worthless-line-wrapping> Program file test.cpp contains only the following line: #include <boost/thread/condition.hpp> [root@mycomputer boost_1_32_0]# "/opt/crosstool/arm-softfloat-linux-gnu/gcc-3.3.3-glibc-2.3.2/bin/arm-so ftfloat-linux-gnu-c++" \ -I/usr/local/boost_1_32_0 \ -I/opt/crosstool/arm-softfloat-linux-gnu/gcc-3.3.3-glibc-2.3.2/include/c ++/3.3.3/ \ -I/opt/crosstool/arm-softfloat-linux-gnu/gcc-3.3.3-glibc-2.3.2/include/c ++/3.3.3/arm-softfloat-linux-gnu/bits/ \ -pthread test.cpp In file included from /usr/local/boost_1_32_0/boost/thread/detail/config.hpp:18, from /usr/local/boost_1_32_0/boost/thread/condition.hpp:15, from test.cpp:1: /usr/local/boost_1_32_0/boost/config/requires_threads.hpp:47:5: #error "Compiler threading support is not turned on. Please set the correct command line options for threading: -pthread (Linux), -pthreads (Solaris) or -mthreads (Mingw32)" [root@mycomputer boost_1_32_0]# </exemplar> I tried working my way through the config headers and got TOTALLY lost. I tried -H, -E and #warning before I gave up and submitted this missive. Even if you can provide the answer "off the top of your head", would you mind providing a pointer or two toward the correct path to finding the problem? I'd appreciate that at least as much as the solution itself. Sincere thanks in advance, Dick Bridges "For every complex problem, there is a solution that is simple, neat, and wrong." H.L. Mencken