Hi, the thread_group::create_thread takes a const function0<void> parameter: thread* create_thread(const function0<void>& threadfunc); The function0 implies already a memory allocation. The templated version look like: template <class Threadable> thread* thread_group::create_thread(Threadable threadfunc) { // No scoped_lock required here since the only "shared data" that's // modified here occurs inside add_thread which does scoped_lock. std::auto_ptr<thread> thrd(new thread(threadfunc)); add_thread(thrd.get()); return thrd.release(); } Which works faster because no need to allocate memory for the boost::function0<void()>. Anthony, if there is nothing wrong, could this substitute the create_thread function in next Boost::thread release? Best regards _____________________ Vicente Juan Botet Escriba