I'm using boost 1.53 on windows 7. I have a main loop which runs some checks and when events are received, results in callbacks that add tasks onto a queue. I then pull a task off the queue, wish to start a thread (and only one thread) to handle the task, and continue to loop checking for certain events. And each time I go through the loop, I want to check to see if the current thread has completed before pulling off another task to process. My problem is that I'm not sure how to write the thread in to do this and not join because I have to keep looping to check for certain events. void my_callback(...); MyTask *task; while (true) { event_checks(); switch(state) { case STATE1: if (!queue.empty()) task = queue.front(); // ... break; case STATE2: // check if thread is still running, otherwise, start new thread boost::thread(&MyTask::do_it, task); // ... break; // ... } I tried things similar to the below but couldn't get that quite right. boost::thread t; while (true) { // ... if (t.timed_join(0) == false) { t = boost::thread(&MyTask::do_it, task); } // ... Any help much appreciated.