Liberal peacebuilding is at the center of a critical debate amongst scholars and practitioners due to the horrific consequence of conflict relapse or escalation in the wake of failed international interventions. Despite international efforts to promote durable peace, empirical research suggests that up to one half of all civil wars relapse into conflict within five years of negotiated settlement (Collier & Hoeffler, 2002; Suhrke & Samset, 2007). As an alternative to top-down liberal peace, locally-led post-conflict peacebuilding has been proposed as an innovative solution (Mac Ginty & Richmond, 2013). Participatory deliberative democracy, when applied in post-conflict contexts, aligns with this ‘local turn' by supporting ‘hybridity’ in peacebuilding practice. However, its potential for contributing to sustainable peace has not yet been empirically tested. This dissertation explores how two post-conflict nations in Central America—El Salvador and Guatemala—have implemented participatory deliberative democracy mechanisms following civil war and the impacts of these mechanisms on the long-term peace process. Combining theoretical frameworks from across political science, economics, and conflict resolution disciplines alongside an international comparative mixed methodology, this study identifies the impacts associated with participatory deliberative democracy over time in two Central American post-conflict countries and the structural and contextual factors that influence deliberative decision making as a possible mechanism to support lasting peace following civil war.