There is growing evidence that the middle school years are critical to students' long-term success. In New York City, middle schools have been the target of several high-profile improvement initiatives. One factor that has the potential to facilitate or complicate these efforts is the stability of the middle school teaching force. Yet there have been few studies of the rates and patterns of teacher turnover in the City's middle schools. The Research Alliance for New York City Schools has recently completed a three-year investigation of teacher turnover that addresses this gap. The study represents the most current, comprehensive look at middle school teacher turnover to date, illuminating how long middle school teachers have historically remained in their schools, how long they intend to stay, what predicts whether or not they leave their school, where they go when they leave, and how their perceptions of their work environment influence these decisions. This summary presents highlights from the report, "Who Stays and Who Leaves? Findings from a Three-Part Study of Teacher Turnover in NYC Middle Schools." It focuses on aspects of the study's results that are likely to be most useful for policymakers and school leaders as they strive to maintain and manage an effective teacher workforce. [For the Technical Appendices for this report, see ED561055.]