Analyses of transitional justice processes conventionally address the formal steps taken by national governments and international political institutions. This article instead focuses on the under-appreciated role of non-state actors in this increasingly important arena of human rights practice. The author extends the literature by developing a theoretical framework, based on broad comparative analysis, concerning the involvement of civil society in these processes. In particular, ‘demand’ and ‘supply’ factors that support and impede such contributions are identified, various roles that NGOs and civic associations perform are enumerated, and the implications of different scenarios of engagement for the development paths of transitional political societies are considered.