Hi there, just to clarify: The pool documentation says in the "Object Usage vs. Singleton Usage" section (see here: http://www.boost.org/doc/libs/1_43_0/libs/pool/doc/interfaces.html): "Pool objects with Singleton Usage may be shared; thus, Singleton Usage implies thread-safety as well." So, with the singleton pool interface I can safely do concurrent mallocs and frees on all supported OSs (using Boost.Thread for the concurrency part), albeit at the expense of having a YASWIOI (yet another singleton with its own interface) in my programs, with all pros and cons that singletons have ? Thanks and Kind Regards, Ruediger Berlich