The role of online communities is a key element in free and open source software (F/OSS) and a primary factor in the success of the F/OSS development model. F/OSS communities are inter-networked groups of people who are united by a common interest in F/OSS software. This chapter addresses holistic issues pertaining to member participation in F/OSS communities, specifically considering their reasons and motivation for participating. It collates the relevant literature on F/OSS community participation and presents the results of an empirical study into members’ perceptions of their own participation. We identify primary reasons for participation such as problem solving, support provision, and social interaction and rank their importance by the participants’ preferences. We then separate development and support activities and compare the community members’ perceptions of the two. Finally, we draw conclusions and discuss the potential for future research in this area.