The integration of external stakeholders in firms' NPD process has found increasing interest in business research and practice. Central to this topic are virtual innovation communities managed by firms in order to facilitate the exchange with external stakeholders and in order to involve them in the different stages of the NPD process. To date empirical research on the drivers of participation of these external stakeholders in virtual innovation communities is lacking. The authors test a comprehensive model of how perceived benefits, individual member characteristics and relational characteristics influence members' participation behavior in virtual innovation communities. The results indicate that hedonic benefits, competence and affective commitment to the virtual network play a crucial role in determining participation behavior in innovation communities.