This book reconstructs the transnational history of the category of Latin American music during the first half of the twentieth century, from a longer perspective that begins in the nineteenth century and extends the narrative until the present. It analyzes intellectual, commercial, state, musicological, and diplomatic actors that created and elaborated this category. It shows music as a key field for the dissemination of a cultural idea of Latin America in the 1930s. It studies multiple music-related actors such as intellectuals, musicologists, policymakers, popular artists, radio operators, and diplomats in Argentina, Mexico, Brazil, the United States, and different parts of Europe. It proposes a regionalist approach to Latin American and global history, by showing individual nations as both agents and result of transnational forces—imperial, economic, and ideological. It argues that Latin America is the sedimentation of over two centuries of regionalist projects, and studies the place of music regionalism in that history.