This paper provides empirical evidence about how free/libre open source software development teams self-organize their work, specifically, how tasks are assigned to project team members. Following a case study methodology, we examined developer interaction data from three active and successful FLOSS projects using qualitative research methods, specifically inductive content analysis, to identify the task-assignment mechanisms used by the participants. We found that ‘self-assignment’ was the most common mechanism across three FLOSS projects. This mechanism is consistent with expectations for distributed and largely volunteer teams. We conclude by discussing whether these emergent practices can be usefully transferred to mainstream practice and indicating directions for future research.