In 2011, President Barack Obama and Secretary of Education Arne Duncan provided states with an opportunity for flexibility from certain requirements under the Elementary and Secondary Education Act, or ESEA, currently known as the No Child Left Behind, or NCLB, Act. A total of 43 states; Washington, D.C.; Puerto Rico; and eight districts in California that are part of the California Office to Reform Education, or CORE--have since received waivers from the U.S. Department of Education. This report uses detailed case studies to look closely at four states--Indiana, Maryland, Missouri, and Ohio--and the unique structures each has put in place to keep track of locally developed teacher-evaluation systems. The U.S. Department of Education waivers were created in response to the almost unanimous agreement that No Child Left Behind is broken. Elementary and Secondary Education Act waivers provide an opportunity for states and districts to move past an outdated system of teacher evaluation given the constraints of NCLB. When it comes to teacher-evaluation implementation, what becomes immediately clear from examining ESEA waivers is that the devil is in the details. It is one thing to have a good plan; it's another thing for that plan to be implemented with fidelity, particularly given the enormous demand on the capacity of state and local educational systems. While the speed with which states and districts have revamped or created new teacher-evaluation systems has been impressive, these systems may not be fully and successfully implemented for years. To ensure that teacher-evaluation systems are set up for the long run, states should start with the evaluation plans outlined in ESEA waiver applications and then consider the following key takeaways related to teacher-evaluation implementation from the early-adopter states profiled in this report: (1) Develop a clear idea of what successful implementation of teacher evaluation looks like; (2) Commit to continuous improvement; (3) Build capacity at the local level; (4) Create clear communication cycles around data with state departments of education and school districts; and (5) Develop systemic relationships between state and district leaders. State and locally developed timelines for the implementation of teacher-evaluation systems make it challenging for the U.S. Department of Education, states, districts, and education advocacy groups to track how districts' evaluation systems are progressing. However, the ESEA waivers have provided an opportunity for states and districts to take more control of reform efforts at the local level and have greater influence over the process.