This paper is concerned with the theoretical deduction and network based analysis of user roles in a public sector online participation project. In this exploratory study we investigate the heterogeneity of community participants, by deducing typical roles, the development over time and possible influences on the overall community building process. The more comprehensive understanding of the underlying network structure will contribute to a better understanding of Open Government activities in general. We find different user roles to differ in kind and quality of their contributions in creating, shaping, and disseminating Open Government activities. The communication and contribution behavior of individuals as well as the identification of different user roles was analyzed by using social network analysis (SNA).