The social dynamics of player communities in online games have been the subject of much research during the last decade. Following a systematic review of empirical research publications from 2000–2010, this article synthesizes the key methods and concepts researchers have used to study and characterize player communities. It also synthesizes the key aspects and operationalizations researchers have concentrated on. The analysis shows that qualitative approaches have been more common than quantitative ones. The concepts used to characterize player communities were often not clearly defined or overlapped in meaning. Yet they revealed a prevalence of micro (groups or teams), meso (guilds or organizations) and macro (communities and networks) perspectives. About 22 different aspects and operationalizations of player communities were identified. Six were most common, i.e. culture and social norms, social structuring, rationale, number of members, used information and communication technologies and time of existence. The article concludes with several suggestions for future research.