Starting from a body of literature on movements around "biological citizenship," this article analyses the political significance of HIV-positive people's collective action in Tanzania. We explore reasons for the limited impact of Tanzanian AIDS activism on the wider political scene, concluding that the formation of a "movement" is still in its infancy and faces many constraints, though some breakthroughs have been made. Participation in PLHA groups in Tanzania encourages politicizing struggles over representation, democratic forms and gender that can lead to a process of political socialization in which members learn to recognize and confront abuses of power. It is in such low-level, less visible social transformations that the greatest potential of participation in collective action around HIV/AIDS in Tanzania lies.