Managing change in the security and justice sector is politically sensitive and incredibly complex: it interferes with the foundations of power, is politically contested at both ends of the development partnership, and potentially challenges the interests of established social and political groupings in partner countries. In consequence, international support for security and justice development programming needs to be designed, organised and delivered in ways that adhere much more closely to the political and operational realities of fragile environments. This report analyses programmes in developing countries, extracting relevant policy implications and providing important lessons for future programmes. It draws on experience from nine security and justice programmes in four different countries: Burundi, Guatemala, Timor-Leste, and Sierra Leone, and highlights what has worked and what has not worked in the design and implementation of security and justice programmes in fragile and conflict-affected states.