In teaching newcomer students, educators must envision how to provide opportunities for language use and development through age-appropriate content instruction. This article describes a design research study, in which we developed and piloted 5th grade science units and studied the participation of two newcomer students in sense-making interactions with peers. By analyzing their participation over a school year, we provide a vision of newcomers' language development that is integrated with, rather than a prerequisite for, disciplinary work. Newcomers' language development involved expanding the interactional moves they used to participate in scientific sense-making, including moves that might be considered purely 'social', but were essential to collaboratively enacting disciplinary practices. In addition, their positioning in small group interactions impacted affordances for participation and language use. Over time, students shifted their positioning, which coincided with improved participation and collaborative sense-making for newcomers and their peers. We offer implications for how teachers can create integrated classrooms that support newcomers' language development and disciplinary learning.