Using statewide data from Tennessee over more than a decade, this paper estimates the job performance returns to principal experience as measured by student, teacher, and principal outcomes. I find that principals improve substantially over time, evidenced by higher student achievement, higher ratings from supervisors, and lower rates of teacher turnover. However, improvement in student achievement as principals gain experience does not carry over when principals change schools. The returns to school-specific experience are largest for principals in high-poverty schools, highlighting the potential benefits of policies to improve the recruitment and retention of high-quality leaders in hard-to-staff environments.