Hello, I find the catch(...) clause in the thread_proxy function (thread.cpp) causing more harm than good. If exception "leaks" from a function executing in the context of a thread, the thread silently goes away but the application continues to operate as if nothing happend. I think, in this instance, the library simply "does too much" by trying to do the cleanup. As a user, I can always wrap the code in the catch-all, but what I cannot change is the fact that when unhandled exception is thrown, I will not see the function in the stack trace where the exception originated. Here is the proposed proxy, after trivial changes: extern "C" { #if defined(BOOST_HAS_WINTHREADS) unsigned __stdcall thread_proxy(void* param) #elif defined(BOOST_HAS_PTHREADS) static void* thread_proxy(void* param) #elif defined(BOOST_HAS_MPTASKS) static OSStatus thread_proxy(void* param) #endif { thread_param* p = static_cast<thread_param*>(param); boost::function0<void> threadfunc = p->m_threadfunc; p->started(); threadfunc(); #if defined(BOOST_HAS_WINTHREADS) on_thread_exit(); #endif #if defined(BOOST_HAS_MPTASKS) ::boost::detail::thread_cleanup(); #endif return 0; } } Regards, Slawomir