The past decade has been marked by rapid changes in teacher evaluations. While many districts and states announced their intention to install better systems, they faced political and structural challenges. In this study, [National Council on Teacher Quality] NCTQ examines evidence of the impact of teacher evaluation in six places (four districts and two states) that have stayed the course in developing and implementing improved teacher evaluation systems: Dallas Independent School District, Denver Public Schools, District of Columbia Public Schools, Newark Public Schools, New Mexico, and Tennessee. The districts and states highlighted here have surmounted challenges to implement successful teacher evaluation systems that are yielding substantial benefits.