The term "turnaround schools" has become an increasingly important phrase in the education lexicon in recent years. Although it is sometimes used generically when talking about schools that have rapidly and significantly increased student achievement, it often is applied more narrowly to schools in which districts used a strategy of replacing principals and teachers to jump-start school improvement efforts. This second definition has even made its way into federal policy, with the U.S. Department of Education specifying a turnaround model as one of four options for low-performing schools. Most principals have read about and heard presentations about characteristics of effective schools. However, that research base was missing a critical piece. What is needed in many schools across the country is guidance for how to jump-start substantial change. This evolving knowledge base on turnarounds--building from research both inside and outside education--provides clear direction for strategies school leaders and their schools can implement in their improvement efforts. The author suggests that principals use the lessons learned about school turnarounds to support school improvement.