Virtual interorganizational communities of practice (IOCoPs) enable professionals in different organizations to exchange and share knowledge via computer-mediated interactions. Prior literature mainly focuses on internal motivating factors at the individual level. However, knowledge sharing requires social interactions thus influences from external entities play an important role in individuals' community participation. In this research, we study external motivating factors generated from two different channels: peer effects within and organizational influences outside the virtual community. We apply a novel econometric identification method to analyze a virtual IOCoP in the financial trading sector. We find that external motivating factors from online peers and offline organizations are influential in determining community participation. In addition, our results suggest that virtual IOCoPs and organizations are two complementary learning channels. Differentiating motivating factors across multiple levels enables us to shed new light on various mechanisms with which IOCoPs can engage collective learning and knowledge management across organizations.