Peacebuilding thinking and practice have evolved significantly over the past decade. The business case for the effectiveness of peacebuilding has been established. Successful interventions underscore the importance of peacebuilding initiatives, as do the high-profile failures that occur when peacebuilding is absent, fragmented or insufficient. With the emergence of new approaches to peacebuilding led by the United Nations Peacebuilding Architecture Review, this paper examines the state of peacebuilding operations and finance in fragile contexts and, building on established trends and debates, identifies four areas that could be critical for driving progress on peacebuilding over the next decade. The paper is one of ten working papers supporting States of Fragility 2020. Together with the papers entitled "Diplomacy and peace in fragile contexts", "Conflict prevention in fragile contexts", and "Security actors in fragile contexts", It provides a comprehensive background to Chapter 2 on peace in States of Fragility 2020. This working paper was authored by Jonathan Marley, Policy Analyst in the Crises and Fragility team of the Global Partnerships and Policy Division (GPP) in the Development Cooperation Directorate (DCD) of the OECD. The paper, which is a background document to States of Fragility 2020, was written under the supervision of Cyprien Fabre (Policy Analyst, GPP/DCD) and Paloma Durán y Lalaguna (Head of Division, GPP/DCD). The author would like to thank Harsh Desai for supporting the development of Chapter 2 in this paper. Noting that all errors and omissions are his own, the author would also like to acknowledge the guidance, support and encouragement of Erik Forsberg, Kathleen Forichon, Cushla Thompson and Cyprien Fabre (OECD); Peter Batchelor & Rachel Scott (UNDP); Sara Batmanglich (World Bank); Hugh Macleman (World Food Programme), Jago Salmon (SIPRI/Centre for International Cooperation), Tyler Beckelman (USIP) and all of the members of the States of Fragility 2020 reference group. Thank you to Susan Sachs for her editorial support. Boxes Box 1.1. Zimbabwe: Fragility and peace Box 1.2. What is peacebuilding? Box 1.3. Political will and security sector reform Box 2.1. Non-DAC countries are prominent providers of ODA to fragile contexts | 7