On a number of key dimensions—the intensity of violence, the military and organizational capacities of insurgents, and the depth of the cultural, social, and political roots of armed rebellion—the conflict in Northern Ireland long appeared more intractable than that in the Basque region of Spain. Yet a negotiated settlement was reached in Northern Ireland, while such attempts to end the Basque conflict have failed over the last decade. My project seeks to explain these divergent outcomes through a comparative investigation of the successful Irish and failed Basque peace processes, focusing on the decision-making of insurgent elites, the legitimacy struggles they must wage, and the structural and cultural fields that facilitate and constrain the transitioning of insurgent movements from violence to democratic politics. I argue that peace-seeking insurgents face three key sets of constraints: those stemming from the organizational structure of the insurgent movement; those imposed by state democratic structures and counterterrorist policies; and the ideological and moral barrier to “negotiating with terrorists” in democracies. I emphasize the interactive and dynamic nature of attempts to disengage from violence by showing how these structural and cultural factors not only constrain or facilitate political action, but are themselves shaped and reshaped by political action.