Other than the current approach (which I agree is not acceptable), I see 6 alternatives to the uuid::create() function. I believe all of them have been mentioned before. 1. Make the random number generator a static object. Document the function as not thread safe. This will be fast, but easy to use incorrectly (e.g. in a multi-threaded program). 2. Make the random number generator a static object and protect calls to it with a mutex. This is a thread safe solution, but it will be slow because of the mutex. 3. Make the random number generator live in thread local storage. This will be a thread safe solution, but requires Boost.Thread. 4. Use the current seed as the random numbers directly. Will this solution provide 'good' uuids? That is, is this source of random numbers good enough? 5. Create a function object (that has the random number generator as a member) that produces uuids. Is this too complicated? i.e.: class uuid_generator { public: uuid_generator() { engine.seed(get_seed()); } uuid operator() const; private: Engine& engine; }; 6. Create a CAS/lock-free random number generator. This is hard to implement. I am favoring number 4, unless it will not produce good uuids. Then I favor number 5. I guess I am looking for direction as to how to proceed. Andy.