schools and students benefit from effective teachers; promoting ongoing professional growth that is aligned with the schools' goals; and retaining and developing teacher leaders. As districts implement and build on this plan, teachers and the public can assess the results and better understand how a comprehensive pay system can support school improvement. It is increasingly clear that the single-salary schedule must be re-designed for a new generation of teachers. Experimentation with performance-based pay is now widespread, with plans in place in Texas, Minnesota, Florida, Alaska, Iowa, North Carolina, Missouri, Kentucky, and other states. President Obama has announced his intention to significantly expand performance-based pay through the federal Teacher Incentive Fund, which would, under his proposal, increase in size from $97 to $483 million ( Washington Post 2009). Our understanding of the short- and long-run implications of these pay schemes is, however, quite incomplete. With most teacher pay reforms only a few years old, it is still too early to empirically evaluate their effects on achievement and the labor market for teachers. The two studies in this volume go a long way toward identifying the dimensions of pay-for-performance that deserve greater attention from researchers and policy makers. Johnson and Papay's new framework for teacher compensation constitutes a bold departure from the single-salary schedule that nevertheless builds on its strengths. They propose a system that is much more than a narrow formula linking pay to student outcomes, in which teachers themselves are relatively interchangeable. On the contrary, Johnson and Papay envision a