In 2005, world leaders made a unanimous commitment to the responsibility to protect (R2P) principle. This Handbook provides a comprehensive assessment of the theory, politics, and practice of R2P, which interrogates its place in world politics and key international institutions, its impact and relationship with the most significant contemporary crises and its future trajectories. In so doing, this book provides a one-stop ‘shop’ for R2P focused around seven themes: ‘history’—examining the evolution of sovereignty, responsibility, and humanitarian intervention; ‘theory’—evaluating the key normative and conceptual puzzles provoked by R2P; ‘institutions’—examining the implementation of R2P through global institutions, especially the UN; ‘regional perspectives’—charting how different parts of the world relate to R2P; ‘cross-cutting themes’—focusing on its relationship with peacebuilding, peacekeeping, gender, protection, and other thematic issues; ‘cases’—exploring how R2P relates to the most pressing international problems; and ‘future trajectories’—where leading thinkers and practitioners reflect on the norm’s future.