This article advocates a shift in teacher knowledge and beliefs about the role of group work in the teaching and learning of emergent bilingual students. Employing case study data from an eighth grade classroom, this article explores the role of collaboration in the interaction with grade-level text of emergent bilingual students. The analysis shows that the quality of collaboration mediates in significant ways the opportunities available to emergent bilinguals for both content and language learning. The article proposes that expanding students’ repertoires of practice to cover collaborative learning should be a worthwhile instructional goal in mainstream classrooms. The article problematizes the currently dominant view of group work as an instructional strategy, and supports the positioning of collaboration as a key disciplinary practice in the new college and career readiness standards. The article offers a conceptual framework for contrasting different types of collaboration that is based on Engeström's (1993) activity theory.