In this paper we examine the relationship between social movements and the police through an analysis of the Civil Rights Movement (CRM) which emerged in the late 1960s in Northern Ireland. Following della Porta (1995) and Melucci (1996) we argue that the way in which episodes of collective action are policed can affect profoundly both levels of mobilization and the orientation of social movements. We also submit that the symbolic and representational dimensions of policing can be a significant trigger in the stimulation of identification processes and collective action. The paper concludes by questioning some of the assumptions contained within social movement theory, and their applicability to divided societies such as Northern Ireland.