Mentoring has become an extremely popular policy for improving the retention and performance of new teachers, but we know little about its effects on teacher and student outcomes. I study the impact of mentoring in New York City, which adopted a nationally recognized mentoring program in 2004. I...

The gap between the qualifications of New York City teachers in high-poverty schools and low-poverty schools has narrowed substantially since 2000. Most of this gap-narrowing resulted from changes in the characteristics of newly hired teachers, and largely has been driven by the virtual...