We present a model for understanding and analyzing participation in social online services and online communities. The model is based on earlier research literature, and contains community elements such as policy, privacy, trust, motivation and roles that influence and are influenced by participation activities. To further specify the model, we conducted a qualitative study consisting of interviews on participation in online communities. Subsequently, we organized an online survey that aimed at validating the elements presented in the model and the ways the elements influence each other. In addition to supporting the validity of the model, the findings present a fresh overview of the respondents’ perceptions of participation in social online services and online communities. The model can be utilized in future studies for example to conduct statistical analysis on participation in online communities. Furthermore, the model can be useful for community organizers when starting to design a social online service that supports online community activities.