This Handbook brings together 30 state-of-the-art essays covering the essential aspects of global security research and practice for the 21st century. * Embraces a broad definition of security that extends beyond the threat of foreign military attack to cover new risks for violence * Offers comprehensive coverage framed around key security concepts, risks, policy tools, and global security actors * Discusses pressing contemporary issues including terrorism, disarmament, genocide, sustainability, international peacekeeping, state-building, natural disasters, energy and food security, climate change, and cyber warfare * Includes insightful and accessible contributions from around the world aimed at a broad base of scholars, students, practitioners, and policymakers