The Caribbean played an important military and strategic role during the Second World War that has not been sufficiently acknowledged in the numerous studies of that global conflict. They generally focus on major theatres of combat such as Europe or the Asia-Pacific region. However, the Caribbean also played a vital role in this conflict. Despite the importance of the topic, published scholarship on Puerto Rico’s involvement in the global conflict and its domestic impact was scarce until recently. Indeed the editors believe that Puerto Rico’s postwar transformation cannot be grasped without tracing its roots to the war years. However, most of this research has been published in Spanish and has not been readily accessible to English language readers. This book, though not a history of the war years in Puerto Rico, aims at providing readers with important insights on the multifaceted impact of the war, while opening a window to recent scholarly research. The authors of Island at War approach the war years in Puerto Rico with emphasis on military, political and economic aspects, but they also make reference to the relevance of cultural, social and human aspects. The essays, though representing diverse perspectives, are closely interrelated. Taken together, they provide a broad view and valuable insights on the crucial importance of the Second World War for Puerto Rican history and US-Puerto Rico relations.