This article explores how peer and teacher–student interactions in linguistically diverse high school English as a Second Language (ESL) classrooms produce changes in learners’ uptake of different languages and cultures. Data presented are from a 2‐year ethnography of communication focusing on adolescent multilingual English learners’ language use in three ESL classrooms in the United States. The study participants’ primary languages were French, Lingala, and Tshiluba, and the dominant language spoken by the students in class was Spanish. The data include recordings of peer group classroom interactions, individual and focus group interviews, and field notes from classroom observations. Analyzed through an ecology of language framework (van Lier, 2004) and heteroglossic perspectives on language learning and use (Bakhtin, 1981), the findings reveal a gradual ideological and pragmatic shift among the focal students from resenting the predominant use of Spanish by their teachers and peers during Year 1 of the study to using Spanish words and phrases during Year 2 for two distinct purposes: peer socialization and learning English. The article concludes by highlighting the importance of attending to students’ language experiences to harness metacognitive thinking, critical multilingual language awareness, and linguistic creativity.