The international community increasingly promotes referendums as it intervenes in self-determination conflicts around the world. However, the ability of self-determination referendums to bring about peace remains uncertain. This paper develops the argument that the conflict resolution potential of self-determination referendums is conditional, depending on whether or not they are held under the mutual agreement of the conflict parties. When mutually agreed, self-determination referendums are likely to generate shared perceptions of fair decision-making and thereby increase chances for peace. By contrast, unilateral self-determination referendums are likely to increase ethnic grievances and, therefore, the risk of separatist violence. I find support for this argument in a global statistical analysis, a series of short case studies, and a survey experiment. Overall, this study suggests that self-determination referendums can make a positive contribution to peace, but only if the conditions for a partial compromise on a referendum, including its terms, are ripe.