Designing peace agreements that can be signed and sustained can be difficult in civil conflict. Many recent cases of successful settlements include electoral provisions, often for rebel groups to participate as political parties. Engaging the electoral process, however, can also open the peace process to the population at large, potentially derailing a settlement or some of its provisions, perhaps especially those related to politics. In this paper, we examine popular support for peace processes, specific electoral provisions, and potential concessions that provide former rebels with protections, legitimacy, and power. Using a survey experiment in Colombia, we find that the peace process overall is more popular than its electoral provisions, and that rebel endorsement of the provisions further diminishes support. These results contribute to an explanation of why the 2016 Colombian plebiscite on the peace agreement failed and to an understanding of how design matters to agreement effectiveness.