The purpose of this Research and Policy Brief is to provide state and local policymakers with a comprehensive understanding of the measures used in teacher evaluation--their strengths, limitations, and current use in policy and practice. This brief will underscore aspects of evaluation policies currently aligned with best practices as well as illuminate areas where policymakers may improve evaluation rules, regulations, and their implementation, thereby improving teacher instruction and student performance. [This paper was written with Sabrina W. M. Laine.]