This article explores the roles of the indigenous Nahuatl language in the production of the imagined nation of Aztlán, a central idea in the US Chicano Movement. It adopts a theoretical approach from linguistic anthropology, attending to the role of language as a source of historical knowledge about the past and also as a medium for the production of metahistorical narratives. It describes the history of the Nahuatl language and its speakers and how the idea of Aztlán has been used first as a source of identity among the Nahuatl-speaking peoples of Mexico, then as a symbol of Mexican national origins, and finally as a source of identity and dignity among Chicano people in the United States. It is argued that just as the Nahuas saw the Nahuatl language as defining a pan-Nahua identity including politically separate city-states, today Chicanos use the Nahuatl language and its related cultural practices to embody a transnational community.