This paper presents findings from a study conducted in an urban elementary school in the United States with an English language learner (ELL) student and two teachers engaged in collaborative teaching in an inclusion science classroom. This study examines the efficacy of utilising cogenerative dialogues between an ELL student and his science teacher and English as second language teacher to improve instructional practices enacted during coteaching. Drawing from field notes, teacher and student interviews, and video captured during cotaught science lessons and during cogenerative dialogues between the student and his coteachers, we examined the ways in which cogenerative dialogue expands teachers' agency to adapt curriculum and implement instructional strategies that can better meet the needs of their students. At the same time, we examined the ways in which participation in cogenerative dialogues with his teachers expanded this student's agency as a science learner and a language learner.