In 1964, the Organization of American States (OAS) and the Institute for Hispanic Culture (ICH) sponsored a lavish music festival in Madrid that showcased the latest avant-garde compositions from the United States, Latin America, and Spain. Critics reserved much of their praise for the serial works, such as Alberto Ginastera's Don Rodrigo Symphony and Gustavo Becerra's Wind Quintet. Recently, various scholars have asserted that during the Cold War, avant-garde music--especially that employing serial techniques--promoted ideologies of freedom, anti-Communism, and scientific exploration. However, much of this research has focused on relations between the U.S. and Western Europe, leaving other Cold War battlefields, such as Latin America, on the periphery. Formed in 1948, the OAS became a virulently anti-Communist organization, disrupting Leftist movements in Latin America in the name of inter-American cooperation. In the 1960s, the OAS reached out to Spain, as it found Franco's anti-Communist stance and the country's cultural ties with Latin America particularly attractive. During the festival, tropes about solidarity that typified OAS discourse intertwined with commentary on the avant-garde. Serialism, touted as a "universal" language, became symbolic of Latin American progress, while nationalistic styles were labeled as divisive. Likewise, the new generation of Spanish composers, led by Cristóbal Halffter and Luis de Pablo, professed to leave Spain's nationalist musical legacy behind, and attempted to reshape Manuel de Falla's image from that of nationalist to innovator. Still, like many composers from countries on the margins of Western music, the Latin American and Spanish composers experienced a doubly binding paradox, wherein to be valued by the European serialists, they must also retain their difference: their Spanish "essence." I propose to problematize the debates about nationalism and the avant-garde of the early 1960s by drawing upon the rhetoric generated by both critics and composers during the Madrid festival. Moreover, as this festival dovetailed with Kennedy's Alliance for Progress, an important Cold War project aimed at Latin America, I also deconstruct the nuanced rhetoric of the festival, which reflected centuries of interaction among the Americas, and helped advanced U.S. political goals with regards to Latin American foreign policy.