This document discusses collaboration on three projects: Protégé, BioPortal, and CEDAR. Collaboration on Protégé happens spontaneously through active mailing lists and users, and is self-reinforcing with thousands of engaged users. Collaboration on BioPortal is more modest due to its large user base and lack of a plugin architecture. Collaboration on the newer CEDAR requires explicit strategy, coordination, and funding as it involves changing user workflows. The document concludes that while collaboration can emerge naturally, complex systems like CEDAR require planned, managed, and funded collaboration efforts.