As the use of open source software gains popularity, it is important to understand the factors that contribute to the success of open source software development projects. This research contributes to this understanding by developing a set of propositions about the organizational structure that supports open source software projects. We argue that in open source software development it is important to understand the existence and interaction of two related but distinct entities; the interest community and the software development group. We propose relationships between the development group, the interest community and software complexity in open source software development. Implications of the propositions for research and practice are discussed.