The mechanism of disarmament, demobilization, and reintegration (DDR) is widely acknowledged to be an essential component of successful peacekeeping, peace-building, postconflict management, and state-building. Security sector reform (SSR) has emerged as a promising though poorly understood tool for consolidating stability and establishing sovereignty after conflict. While DDR enables a state to recover the monopoly (or at least the preponderance) of force, SSR provides the opportunity for the state to establish the legitimacy of that monopoly.The essays in this book reflect the diversity of experience in DDR and SSR in various contexts. Despite the considerable experience acquired by the international community, the critical interrelationship between DDR and SSR and the ability to use these mechanisms with consistent success remain less than optimally developed. DDR and SSR are essential tools of modern statecraft, but their successful use is contingent upon our understanding of both the affinities and the tensions between them. These essays aim to excite further thought on how these two processes-DDR and SSR-can be implemented effectively and complimentarily to better accomplish the shared goals of viable states and enduring peace.