This report reviews findings from 35 major studies that speak to the question of principal turnover. Within these studies, researchers have examined principal turnover nationally and within states and districts, primarily investigating the relationships between principal turnover and various characteristics of principals, schools, students, and policies. While there is some consistency across studies, there is a good deal of variation in research questions, methods, and measurement of turnover. Further, few studies consider all the possible pathways out of the principalship, and few isolate the ways in which specific conditions or features of the principalship impact principals’ decisions to leave or districts’ decisions to retain principals. Despite these limitations, we found that, when examined together, these studies provided important information to help policymakers, education leaders, and other stakeholders understand and address principal turnover.