‘Hybrid’ open source software communities are conducive to knowledge integration and innovation, and can be seen through a community of practice lens. In this paper, we develop an integrated process theory of structural attributes and social mechanisms of hybrid virtual communities. We offer a dynamic view of knowledge integration and innovation in such communities. We also emphasise the multi-faceted nature of virtual communities and identify factors that regulate participation and sustain such communities. This has implications for theorising about knowledge integration and innovation in hybrid virtual settings. Finally, virtual ethnography and multi-level research are suggested for future research.