Education policy makers have long searched for a system that will recognize and reward outstanding practice, support educators to improve their performance, and, most importantly, increase student achievement. For states and school districts to secure grants from the $4.35 billion Race to the Top (RTTT) Fund, President Barack Obama is requiring them to "use data effectively to reward effective teachers, to support teachers who are struggling, and when necessary, to replace teachers who aren't up to the job." The scale of the federal investment in RTTT is unprecedented, and the four core education reform assurances--rigorous standards and internationally bench marked assessments, data systems tracing individual students and teachers, great teachers and leaders, and turning around struggling schools--send a strong message about the federal government's commitment to systemic change. But the most important among these assurances is the development of effective teachers, a clear indicator that the quality of instruction is now understood as the single most important influence on student progress. Like the No Child Left Behind Act of 2001, RTTT emphasizes the importance of improving teacher quality as a vehicle for accelerating student progress and closing achievement gaps. However, the new policy redefines the indicators used to measure student outcomes--and in turn, teacher effectiveness--by focusing on the growth that individual students make over the course of the year, rather than on their achievement level at a particular point in time. To receive funds, states' RTTT proposals have to include student growth as one of the multiple measures in an enhanced teacher evaluation system and propose plans to use this information in decisions related to compensation, career advancement, and tenure. In fact, states barring the use of student data in teacher evaluation are not even eligible to apply. This essay discusses various positions on current efforts and outlines a series of recommendations for reformers to keep in mind as they design new initiatives. To maximize the potential of these new policies to make good on their promised goals, states will have to build both the capacity and the will to sustain reform. (Contains 2 endnotes.)