The purpose of this article is to review the research on policy and professional development undertaken by the Center for the Improvement of Early Reading Achievement (CIERA) and to suggest how this work has advanced knowledge in these areas. This research provides a base for understanding the relations between effective teaching and learning in reading and the national, state, district, and school policy contexts that mediate classroom practice. The CIERA studies reviewed have consistently shown evidence of improved instruction and student literacy learning in contexts characterized by strong centralized supports, such as leadership within the school and/or district and networks or communities of practice that include strong teacher leaders. These findings lay the groundwork for future investigations of how best to establish such contexts in settings where they do not now exist, and of the resulting effects on students' reading achievement. These findings also have implications for literacy policy research and literacy policy. They suggest that literacy policy research is likely to be most meaningful when it probes deeply into the relations among particular policy contexts, teacher practices, and specific types of student learning. They further suggest the need for accountability mechanisms that operate closer to the student -- that is, at the district, school, and classroom levels as opposed to national and state levels.