Teachers obviously serve as the medium for causing the result of policy as they carry it into schools and classrooms and deliver it to pupils. They mediate between education policy and practice. Knowledge of the exact nature and effects of this vital role is limited. Drawing on a range of research and evaluation of both national and local policy in practice, carried out by the authors in England, this paper illustrates how teachers mediate policy and the resulting outcomes. Further, it proposes a typology of teacher adaptation to education policy. The paper argues that as yet the appropriate professional role for teachers within policy-making and implementation has not been achieved, and outlines what this might be. Finally, it outlines some implications for teacher education. (Contains 3 tables.)