I don't know if thread_group is supposed to stay around now that we have movable threads, but if we're going to keep it I would like to propose a few changes. 1. add_thread should take an auto_ptr<thread> (and eventually unique_ptr<thread>) so the signature indicates the ownership transfer. 2. remove_thread should be called release_thread. "Release" is at least not ambiguous about whether the thing is being destroyed. -- Dave Abrahams BoostPro Computing http://www.boostpro.com