Book excerpt: Multilateral organizations - the United Nations (UN) in particular - have played, and continue to play, an important role in shaping the security sector reform (SSR) agenda, both in terms of policy development and the provision of support to a wide range of national SSR processes. This volume presents a variety of perspectives on UN support to SSR, past and present, with attention to policy and operational practice. Drawing from the experience of UN practitioners combined with external experts on SSR, this volume offers an in-depth exploration of the UN approach to SSR from a global perspective.