Perceptions of L2 teachers have undergone a recent change. No longer viewed as deliverers of a particular methodology, they are now seen as theorizers who develop expertise in their classrooms. Parallel to this shift, L2 teacher education programs have moved away from a transmissive mode to one that encourages student teachers to develop their own theories of teaching and learning. Such theorizing has until now been viewed as coming from interactions with their peers, instructors, supervisors, and classroom teachers. This article argues for the inclusion in teacher education programs of a fifth set of participants—adult L2 learners. The article offers reasons why they should be included, suggests means of tapping their expertise, and describes four ways the authors have sought to bring learners and student teachers together in mutually beneficial ways in their teacher education progra