So far, we know little about how ceasefire monitoring mechanisms support ceasefire compliance and peace processes in civil wars and of the role of domestic civil society in such mechanisms. This paper suggests that this is an important area of focus. Based on evidence from the conflict between Maoist insurgents and the government of Nepal, it shows that civil society monitors’ presence can effectively deter conflict parties from major ceasefire violations, especially in contexts where the parties are looking to access political power. Yet, key issues limit their effectiveness, notably the parties’ political will for the process, the monitors’ ability to remain detached from their political affiliations and ambitions and the design of the mechanisms.