In this volume, essays by scholars from both sides of the Atlantic open new perspectives on the construction of the ‚Atlantic community‘ during World War II and the early Cold War years. Based on original approaches bringing together diplomatic history and the history of culture and ideas, the book shows how atlantism came to provide a solid ideological foundation for the security community of North American and European nations which took shape in the 1940s. The idea of a transatlantic community based on shared histories, values, and political and economic institutions was instrumental to the creation of the Atlantic Alliance, and partly accounts for the continuing existence of the Atlantic partnership after the Cold War. At the same time, this study breaks new ground by arguing that the emergence of the idea of ‚Atlantic community‘ also reflected deeper trends in transatlantic relations; in fact, it was the outcome of the re-definition of ‚the West‘ due to the rise of the US and the decline of Europe in the international arena during the first half of the Twentieth Century.