Underground music file sharing communities are online social spaces that facilitate the sharing of mostly unauthorised digital content. This paper proposes underground file sharing communities as subcultures, and explores the Roswell community from theoretical perspectives of group formation and translation from Actor-network theory (ANT) to gain a better understanding of the motivations for file sharing. Through observations and supporting interviews, a detailed discussion of underground file sharing communities is presented. The discussion reveals interesting insights about the 'black box' of file sharing, and the ideologies of those involved. Scarcity and quality are strong motivators for engaging in underground file sharing communities, with access to high quality music files and scarce music files being a reward for actively participating. The quality of content is maintained through strict rules for converting and uploading new music. Because underground communities are quite sophisticated, it is argued that it is possible to learn from them and use this knowledge in the development of future online music systems and communities.