To write about Indigeneity means already being deeply enmeshed in identity politics. The much researched rural south of Mexico City is a case in point. Anthropologists have described the Nahuatl speakers of Milpa Alta as “heirs of the Aztecs,” and knowledge of Nahuatl and folklore has become key to maintaining municipal land rights in the context of current multiculturalist politics. Thus, Nahuatl has become a politicized marker of prestige. This has led to various tensions, including acrimonious competition over what constitutes the “correct” way of speaking Nahuatl and frictions with newly arrived speakers of other Indigenous languages. To avoid exacerbating these tensions, I suggest that anthropologists should commit to decolonizing their work by politically and epistemologically situating it and by adopting participatory approaches, as well as an iterative, adaptive approach to research ethics. This means continuously reevaluating and tailoring one's ethics to concrete situations as they emerge—and never truly leaving “the field.” [Identity politics, decolonization, Nahuatl language]