Ten years ago, many policy makers viewed the reform of teacher evaluation as a highly promising mechanism to improve teacher effectiveness and student achievement. Recently, that enthusiasm has dimmed as the available evidence suggests the subsequent reforms had a mixed record of implementation and efficacy. Even in districts where there was evidence of efficacy, the early promise of teacher evaluation may not be sustainable as these systems mature and change. This study examines the evolving design of IMPACT, the teacher evaluation system in the District of Columbia Public Schools. We describe the recent changes to IMPACT, which include higher performance standards for lower-performing teachers and a reduced emphasis on value-added test scores. Descriptive evidence on the dynamics of teacher retention and performance under this redesigned system indicates that lower-performing teachers are particularly likely to either leave or improve. Corresponding causal evidence similarly indicates that imminent dismissal threats for persistently low-performing teachers increased both teacher attrition and the performance of returning teachers. These findings suggest that teacher evaluation can provide a sustained mechanism for improving the quality of teaching.

Policy makers and researchers are intrigued with but also frequently frustrated by each other. Although these differences are understandable and predictable, it is clear that research on a variety of educational issues has been both influential and valuable in the development of policy and practice. There is much to suggest that researchers and policy makers should be collaborating to improve student outcomes. There are important instances of sustained collaborations between educational researchers and educational policy makers. We summarize some of these efforts but describe in more detail the Education Finance Research Consortium, a long-standing collaboration between university-based researchers and the New York State Education Department. Given the current intense focus on the role of evidence in the development of education policy, some of the lessons from this collaboration may be useful to those seeking to expand the use of evidence in policies intended to improve student learning.