Abstract
This paper reports on a professional development intervention coupled with an empirical research study focused on a mentor teacher study group. An unanticipated outcome of the study group was an evident development in the sense of accountability displayed by participants toward the work of teacher education in their school. In effect, teachers' identities were transformed from relatively passive cooperating teachers, following the direction of teacher education program guidelines and procedures, to active school-based teacher educators, consciously developing repertoires of mentoring practice, and taking initiative to remake the culture of their school as a context for learning to teach. The paper proposes a theoretical analysis to explain the evolution of accountability among study group members, examines five different examples of how such accountability was manifested, and suggests implications for teacher education programs.