We address the notion that different student grouping configurations in the classroom may provide different sets of opportunities for English learners (ELs) -- students whose home language is not English (the language of instruction in the U.S.) -- to both learn science and develop a second language through different forms of social interaction. We examined the frequency with which monolingual and bilingual (English-Spanish) teachers interacted with students working in four grouping configurations: Only ELs, Whole Class, Only Non-ELs, and Mixed (both ELs and non-ELs). We used a sample of 359 instructional episodes from 78 science lessons taught by bilingual and English-only teachers in the U.S. While we observed a considerable variation in the frequency of different classroom practices (e.g. those promoting critical thinking were less frequent than those involving factual knowledge), Whole Class was the grouping configuration most frequently observed for all classroom practices. The same frequency patterns were observed for monolingual and bilingual teachers. We argue that the low frequency of teachers' interactions with students working in small groups limits the opportunity for ELs to learn science through different forms of social interaction and for teachers to identify and address individual EL students' learning needs.