This edited volume brings together many of the world’s leading scholars of intelligence with a number of former senior practitioners to facilitate a wide-ranging dialogue on the central challenges confronting students of intelligence. The book presents a series of documents, nearly all of which are published here for the first time, accompanied by both overview and commentary sections. The central objectives of this collection are twofold. First, it seeks to build on existing scholarship on intelligence in deepening our understanding of its impact on a series of key events in the international history of the past century. Further, it aims to explore the different ways in which intelligence can be studied by bringing together both scholarly and practical expertise to examine a range of primary material relevant to the history of intelligence since the early twentieth century. This book will be of great interest to students of intelligence, strategic and security studies, foreign policy and international history.