Growing teacher shortages nationally have made filling vacancies with qualified teachers increasingly difficult. Curbing teacher turnover—that is, all teacher movement out of schools or out of the profession—can go a long way toward solving shortages. About 90% of the nationwide annual demand for teachers is created when teachers leave the profession, with two-thirds of teachers leaving for reasons other than retirement. If school systems can address the factors that create high turnover, they can reduce the demand for teachers who are in short supply. Not only does turnover contribute to shortages, teacher movement out of schools and out of teaching creates costs for the schools they leave behind. Estimates exceed $20,000 to replace each teacher who leaves an urban school district. Most importantly, high turnover rates reduce achievement for students whose classrooms are directly affected, as well as for other students in the school.