In earlier studies of classroom second language learning attention was focused on teacher-pupil interaction. However, it is evident that learners learn in many ways, and studies of 'group-fronted' classes suggest that pupil-pupil interaction may lead to more comprehensible linguistic input and more productive and 'negotiated' output. At the level of child second language acquisition, such interaction has been studied primarily as language-in-play, with the focus on learner output, but research on caretaker language and foreigner talk has also led to studies of whether, and how, children simplify, repeat, and expand utterances as they speak with less proficient interlocutors. The present study reports on the 'tutor talk' used in two typical peer situations within a local elementary school: (I) in teacher-directed NNS-NNS (non-native speaker) pairings in the ESL classroom, and (2) in pupil-initiated pairings as native or more proficient non-native English-speaking children help LEP (low English proficiency) children in content-based lessons. It is concluded that, while little sentence-level simplification is used by the tutors, extensive use is made of conversational and tutorial strategies similar to those used by native and nonnative adults. Samples and tabulations are given of the 'tutor talk' used in the six dyads observed. © 1991 Oxford University Press.