Hmm...it's still not working for me. To the code I posted before, I added the call ioService.run(); in the doConnect() routine, after the loop where the connect is done. I get the same behavior: after the async_read_some() is called, I can see the the buffer is updated (so it read what was there), but my handler was never called. I'm sure there's a simpler explanation for my problem, but, FWIW, looking at the stack for the async_read_some call, I see the call to WSARecv(). I don't have much experience with that routine, but I did notice that the last argument(LPWSAOVERLAPPED_COMPLETION_ROUTINE) was hardcoded to 0. This may be correct, but at first glance it seems like that should be a handler to my handler routine. -- =======================