According to standard accounts, twentieth-century music in Latin America was dominated by ‘folkloristic nationalism’. As this chapter demonstrates, however, there has been a number of lively serialist movements that, after gaining a foothold in Buenos Aires in the 1930s, gradually coalesced to achieve a modicum of mainstream and institutional acceptance across much of the region by the 1960s. This story not only provides an important facet of Latin America’s music history, but it also touches on crucial issues beyond that, such as the way artistic innovations are disseminated; the role of migration and national, regional, and international networks, such as the International Society for Contemporary Music (ISCM); the varying connections between aesthetic ideas and ideological and political principles; and debates about progress and tradition, national culture and universalism. The history of serialism in Latin America thus to an extent mirrors that in other regions but adds some specific elements.