This handbook provides a comprehensive analysis of the contemporary theory, practice and themes in the study of national security. Part 1: Theories examines how national security has been conceptualised and formulated within the disciplines international relations, security studies and public policy. Part 2: Actors shifts the focus of the volume from these disciplinary concerns to consideration of how core actors in international affairs have conceptualised and practiced national security over time. Part 3: Issues then provides in-depth analysis of how individual security issues have been incorporated into prevailing scholarly and policy paradigms on national security.