Abstract: In recent decades, Protestant population has grown rapidly in most Latin American countries, including Mexico. The growth has been particularly fast in rural and indigenous areas, where Protestantism is often claimed to trigger profound socio-cultural changes. This article discusses the impact of Protestant growth on customs, collective practices and local identities using the example of indigenous Zapotec communities of the Sierra Juárez in northern Oaxaca. Drawing on the author’s intermittent fieldwork in the region since 1998, most recently in 2012, the article first scrutinises some of the recurring local perceptions of Protestant growth in the Sierra Juárez and their impact on communal life. Particular attention will be paid to converts’ break with various customary practices pertaining to what locally is referred to as usos y costumbres. The article will then critically revise the claims about the culturally destructive influence of Protestantism, suggesting that the socio-cultural changes in contemporary indigenous communities of Oaxaca may actually be caused by more general modernising and globalising forces, and that the transformative role of Protestantism is often exaggerated.