In this ethnographic study, I investigate heterogeneous-language peer interactions in an English-only kindergarten classroom. English Learners and English Proficient students co-created language necessary to build an argument, one discourse valued in schools. Students developed complex oral language proficiency skills but were viewed as engaging in chitchat. Implications include the need for teachers to listen to peer talk, which has potential for social, cognitive, and linguistic development necessary in which to bridge academic discourse.