Many educational policy initiatives use instructional coaching to accomplish their goals. Yet we know little about the role of reading coaches in mediating the relationship between policy and teachers' classroom practice. In this article, we investigate the role of reading coaches in mediating the relationship between Reading First policy and teachers' classroom practice. We conducted an in-depth, longitudinal case study of one urban elementary school in Massachusetts, starting the year before the onset of Reading First and continuing through the first year of its implementation. In our analysis, we focus on seven first- and second-grade teachers, two coaches, and two school administrators. We argue that, although reading coaches were only one of multiple sources from which teachers learned about Reading First policy, teachers were much more likely to make substantial changes in their classroom practice when they learned about the policy message from a coach than from other sources. Coaches influenced teachers by helping them to learn new approaches and to integrate them into their classroom. But, they also did so by pressuring teachers, shaping how they saw and understood Reading First, and by counseling them on which aspects of the policy to focus on and which aspects to ignore. Thus, we present a vision of coaching that goes much beyond its educational roles, to highlight the political roles of the coach as well. We close by drawing implications for research on coaching, policy implementation, and practice. (Contains 10 notes, 1 table, and 3 figures.)