Although more than a million people still speak Nahuatl, this number is rapidly diminishing. Historically, Nahuatl was the dominant language of Coatepec de los Costales, a small village in Guerrero, Mexico. The last 50 years have seen a pronounced shift there from Nahuatl to Spanish. The ultimate cause of language shift is a disruption in intergenerational language transmission as a result of often violent colonial encounters. Using a conceptual framework that combines (1) the primacy of Indigenous knowledge systems, (2) a critical sociocultural approach to language acquisition, (3) Bernard Spolsky's definition of language policy as language practices, ideologies and management, and (4) the ethnography of language policy, this article explores, from a critical Indigenous perspective, the local dynamics and global influences that contribute to the endangerment of Nahuatl. More specifically, it examines the mechanisms through which language ideologies, family-community language management strategies and everyday language practices operate among people of different generations, thereby revealing socialisation practices and Indigenous systems of community-based learning. This work may assist other Indigenous communities in better understanding the multiple mechanisms at play in language loss and reclamation -- spanning educational to environmental contexts.