I've only quickly scanned the POCO web page, but it appears that there is quite a bit of overlap with Boost (and will be even more overlap in the future). In particular: - Threading (existing in Boost, with upcoming enhancements) - Network programming (Asio, in upcoming release) - Streams, Filesystem (FS and Iostreams already in Boost) - Shared libraries, loading (talked about but not in Boost) - Logging, error reporting (submitted but rejected, promised for future Boost review) - Security (not sure if any overlap with Boost) - XML parsing (talked about, urgently needed in Boost, IMO) - Configuration file, options handling (Program Options already in Boost, Property Tree in future release) It might be interesting to compare interfaces, functionality, and semantics, however. Or see if parts of the POCO components should be reworked as needed and submitted for review to be part of Boost. ACE is a very mature, capable, and well-tested set of libraries (despite the initial appearance of some web pages). It has some real advantages (and some disadvantages, mostly dealing with it's age, since it's vintage is close to 15 years). I and others have made comments and given short overviews of ACE in previous Boost postings, so a search through the Boost archives would help. ACE and Boost are quite different in interfaces and approach, so there's not much (if any) mix and match between the two (parallel co-existence works just fine, as I can attest to from experience). Cliff