Since the 1980s, Latin American states have transformed how they understand and classify their populations: from policies deeply rooted in notions of national unity and ethno-racial and cultural homogeneity, these states began to recognize their internal diversity. Following new global multicultural norms regarding diversity and human rights, Chile and Argentina slowly came to grant legal recognition first, to Indigenous peoples, and more recently, to Afrodescendants. However, Argentina and Chile have taken different approaches to recognize the legal status of Afrodescendants, despite both countries historically identifying themselves as nations "without" Black populations. While Argentine law and policies have stressed the importance of ancestry and a broad notion of Afrodescendant culture, Chilean legislation has followed an "indigenous model," defining the "Chilean Afrodescendant Tribal People" in relation to a particular history, culture, and identity connected to a specific territory. My dissertation analyzes how the Argentine and Chilean states arrived at these definitions, examining which actors participate in and which actors are excluded from debates around who is counted as Afrodescendant. Through a multi-sited ethnography, I seek to understand how, in a broader context of ethno-racial revitalization, different local, national, and international actors interact to adopt transnational multicultural norms and repertoires of action in these two different national contexts. Additionally, I inquire into how recent changes in immigration flows affect Afrodescendant movements' claim-making processes amidst Chilean and Argentine ethno-racial politics. My work carries theoretical and policy implications for understanding how these definitions matter for the inclusion and exclusion of different groups in policies and programs that aim to address ethno-racial inequality.