The Routledge Companion to Intelligence Studies provides a broad of the growing field of intelligence studies, acting as a relection of the state of the art of the subdiscipline. Focusing on the origins, practice and nature of intelligence studies, this Companion features essays by an array of international experts. It first explains the generic lessons of intelligence - what it is, how it is collected, and how it is processed. It then dedicates sections to the evolution of intelligence; to key episodes in modern history; and to contemporary and future threats. The importance of these three sections is to highlight how our understanding of 'intelligence' has been shaped by the nature of the 'threat'. A final section offers a comparison of national intelligence systems from around the world, grounding the book in an international context and opening up Western readers to accounts of hitherto fairly unexplored countries such as China, South Africa and Japan. This Companion will be essential reading for students of intelligence studies and strategic studies, and highly recommended for students of defense studies, foreign policy, cold war studies, diplomacy, and International Relations in general.