This article explores the interface between international and local approaches to peacebuilding by analysing the experience of two national NGOs involved in peacebuilding work in Sri Lanka between 2006 and 2008. During this transitional period, Sri Lanka's fragile peace process began to unravel. This analysis uses the lens of NGO legitimacy to reflect on the dilemmas and tensions associated with the liberal peacebuilding project and NGOs' role within it. It identifies a critical tension between liberal cosmopolitan and nationalist models of political engagement, which NGOs and the international donors that supported them struggled to negotiate. It argues that NGOs' efforts to reconcile international and local peacebuilding agendas involve uncomfortable trade-offs, and that these processes of negotiation are influenced by NGOs' concerns about organizational survival.