School Leaders Matter.

It is widely believed that a good principal is the key to a successful school. No Child Left Behind encouraged the replacement of the principal in persistently low-performing schools, and the Obama administration has made this a requirement for schools undergoing federally funded turnarounds. Foundations have invested millions over the past decade in New Leaders for New Schools, an organization that recruits nontraditional principal candidates and prepares them for the challenges of school leadership. And the recently launched George W. Bush Institute is making the principalship a focus of its activities. Yet until very recently there was little rigorous research demonstrating the importance of principal quality for student outcomes, much less the specific practices that cause some principals to be more successful than others. As is often the case in education policy discussions, we have relied on anecdotes instead. This study provides new evidence on the importance of school leadership by estimating individual principals' contributions to growth in student achievement. Our approach is quite similar to studies that measure teachers' "value added" to student achievement, except that the calculation is applied to the entire school. Specifically, we measure how average gains in achievement, adjusted for individual student and school characteristics, differ across principals--both in different schools and in the same school at different points in time. From this, we are able to determine how much effectiveness varies from one nrincinal to the next Our results indicate that highly effective principals raise the achievement of a typical student in their schools by between two and seven months of learning in a single school year; ineffective principals lower achievement by the same amount. These impacts are somewhat smaller than those associated with having a highly effective teacher. But teachers have a direct impact on only those students in their classroom; differences in principal quality affect all students in a given school. We also investigate one widely discussed mechanism through which principals affect student achievement: the management of teacher transitions. Importantly, because high teacher turnover can be associated with both improvement and decline in the quality of instruction, the amount of turnover on its own provides little insight into the wisdom of a principal's personnel decisions. We confirm, however, that teachers who leave schools with the most-successful principals are much more likely to have been among the less-effective teachers in their school than teachers leaving schools run by less-successful principals. The final component of our analysis considers the dynamics of the principal labor market, comparing the effectiveness of principals who move on to those who stay in their initial schools. Constrained by salary inertia and the historical absence of good performance measures, the principal labor market does not appear to weed out those principals who are least successful in raising student achievement. This is especially true in schools serving disadvantaged students. This is troubling, as the demands of leading such schools, including the need to attract and retain high-quality teachers despite less desirable working conditions, may amplify the importance of having an effective leader. The Texas Database Our analysis relies on administrative data constructed as part of the University of Texas at Dallas (UTD) Texas Schools Project. Working with the Texas Education Agency (TEA), this project has combined different data sources to create matched data sets of students, teachers, and principals over many school years. The data include all Texas public-school teachers, administrators, staff, and students in each year, permitting accurate descriptions of the schools led by each principal. The Public Education Information Management System (PEIMS), TEA's statewide database, reports key demographic data, including race, ethnicity, and gender for students and school personnel, as well as student eligibility for subsidized lunch (a standard indicator of poverty). …