A growing body of research recognizes the critical role of the school principal, demonstrating that school principals' effects on student outcomes are second only to those of teachers. Yet policy makers have often paid little attention to principals, choosing instead to focus policy reform on teachers. In the last decade, this pattern has shifted…

The federal Race to the Top competition provided significant impetus for states to adopt value-added models as a part of their teacher evaluation systems. Such models typically link students to their teachers in the spring semester when statewide tests are administered and estimate a teacher's performance based on his or her students' learning…