Collaborative teaching is widely adopted in teacher-training programs in the United States for the positive influence it has on teachers’ professionalism and on students’ learning. Though there are a vast number of studies on the Initiation- Response-Feedback (IRF) sequence between teachers and students, studies on the use of IRF in co-teaching contexts are scarce. The current study focuses on interactions between two pre-service teachers in a semester-long adult ESL classroom at a U.S. university. Through a discourse analysis of the leading and non-leading teachers’ interactions within the IRF sequence, the study has found that the nonleading teacher utilized the second turn of IRF as an interactional resource to advance the instructional talk and achieve the immediate instructional objectives.