My goal is to write a transnational history of the modernization of musical practices in Latin America between 1910 and 1950. My hypothesis challenges the dominant interpretations of the “nation-making” process, by arguing that cultural nationalism, the cultural industry, and even the official discourses and policies regarding the musical symbols of the national identities in the region, were all produced by a series of transnational musical networks that operated within and beyond the national projects. These networks are evident in the following snapshots of the Latin American musical scene around 1930: an American producer arranges samba hits in Rio de Janeiro, while Brazilian and Mexican artists compose nationalist works in New York and Paris. Afro-Cubanistas from Havana are in Paris too, joining intellectuals and artists from all over the world in inventing négritude. In Mexico, a rural teacher makes his peasant students sing folk songs but also asks for scores of Russian ballads to the Educational authorities in the capital, while commercial radio broadcasts Argentine tangos to both rural and urban audiences. At the same time, in Buenos Aires, a Lithuanian immigrant performs a Mexican ranchera in Yiddish, while his fellow immigrants play tango, but also Beethoven and Jewish folk songs. Across the Rio de la Plata in Montevideo, a recently emigrated young German scholar exchanges letters with many of these composers, as well as folklorists and intellectuals, creating the first Latin American musicological network, which will converge, a few years later, with the musical initiatives of US-led Pan Americanism. These snapshots lead us to ask: was the soundtrack of the golden era of nationalism really so “national”? Primary sources located in Argentina, Brazil, Mexico, the United States, and Germany, will provide evidence of the networks that enabled the region’s transnational circulation of ideas, sounds, musicians, and state policies.