"Much of the literature on the behaviour and politics of armed non-state actors towards civilian populations shares a common epistemic goal: To explain the reasons for armed groups to kill or otherwise harm civilian populations. This research project seeks to address the question from the opposite direction. Rather than focusing on the causes of violence towards civilians, the objective is to understand under which conditions we can expect armed non-state actors to exert restraint and spare civilian lives. The assumption is that the factors leading to increased levels of non-state violence against civilians are not necessarily the same as those producing the opposite outcome – that is, absence or reduction of violence. This has important policy implications given that a one-sided focus on the causes of escalation of violence may actually not be sufficient to break the spiral of violence and move towards de-escalation. Taking the Fuerzas Armadas Revolucionarias de Colombia (FARC) as a case study, I argue that growing disaffection among the very people the FARC claimed to represent and protect culminated in a profound crisis of legitimacy. The combination of every day resistance at the local level and other forms of socio-spatial protest initiated by national and transnational/global actors eventually forced the FARC to reconsider its use of violence against civilians and exert restraint in order to avoid organisational decline. To increase the robustness of my findings, a paired comparison will be conducted between the case of the FARC and at least one additional case of contentious interaction between an armed non-state actor and civilian populations.