Concerned about the expense of teacher turnover, its disruption to schools and students, and its potential effect on students' access to effective teachers, the School District of Philadelphia (SDP) partnered with the Regional Educational Laboratory Mid-Atlantic to better understand students' access to effective teachers and the factors related to teacher turnover. The district already engages in efforts to address teacher turnover by supporting new teachers, targeting retention strategies to teacher needs, and improving school climate. Findings from this study can inform these efforts by improving SDP's understanding of the role of turnover in the equitable distribution of effective teachers and by identifying teacher and school characteristics related to turnover. This study focused on SDP teachers who taught kindergarten-grade 12 in school years 2010/11 through 2016/17. Methods used included an intraclass correlation analysis and effective teaching gap analysis, to examine access to effective teachers in the district, and descriptive statistics and a hazards model analysis, to examine the factors related to teacher turnover. [For the full report, see ED607752; for the appendices, see ED607754.]