Principals are a key in-school factor associated with student achievement. When principals leave, it can disrupt school progress, increase teacher turnover, and stall student achievement. A new study developed by the National Association of Secondary School Principals(NASSP) and the Learning Policy Institute (LPI) reviews existing research to identify why school leadership matters and the impacts of principal mobility on student achievement. It looks at the data on principal mobility and ways that policymakers can improve principal retention, especially in schools with higher percentages of students from low-income families, students of color, and low-performing students where turnover is highest. Read more.