Introduction: Virtual communities play an important role in innovation. The paper focuses on the particular form of collective action in virtual communities underlying as Open Source software development projects. Method: Building on resource mobilization theory and private-collective innovation, we propose a theory of collective action in innovative virtual communities. We identify three communal resources (reputation, control over technology and learning opportunities) that appear as a byproduct while developing open source software. Analysis: Constructs are derived from exiting literature. Empirical data from Freenet, an open source software project for peer-to-peer software, illustrates both the levels of involvement and the communal resources. Results & conclusions: Communal resources are able to solve the collective action dilemma for virtual communities. We show that they increase in value for individuals along with their involvement in the community. (Contains 1 table and 13 footnotes.)