I vote to accept asio into boost. Potential bias disclosure: I'm friends with Chris Kohlhoff. I have been writing asynchronous servers and clients with asio and boost for about 20 months. The following asio & boost -based server applications are currently running in commercial production systems: * a gateway from a proprietary networking API to HTTP. Up since November 2004. Windows+VC7. * a custom authenticating HTTP proxy. Up since February 2005. Linux+gcc. * an HTTP gateway to a proprietary IM system. Up since May 2005 except short upgrades to my code. Linux+gcc. * an XMPP (Jabber) gateway for the same proprietary IM system. Up since August 2005 except short upgrades to my code. Linux+gcc. * a lightweight publish-subscribe mechanism. Up since August 2005. Linux+gcc. I've found asio's implementation to be extremely efficient. For example the publish-subscribe mechanism can handle 500 requests/second without any detectable CPU usage on a 3Ghz P4 even though my code is untuned & does more memory allocations than is strictly necessary. I found the asio design philosophy and documentation relatively easy to understand however I before I used asio I had already written aynsc socket applications using Windows' IO completion ports. I am not a template-based design expert nor am I a longstanding boost user. My first use of boost was when I started my first asio application in August 2004. Matt