Productivity returns to experience in the teacher labor market: Methodological challenges and new evidence on long-term career improvement

•We examine the returns to teaching experience using four different approaches.•We document the central methodological assumptions used in each approach.•We present a new approach to estimating within-teacher returns to experience.•We document how even small violations of assumptions can lead to substantial bias.•We find continued returns to experience throughout a teacher's career.

We present new evidence on the relationship between teacher productivity and job experience. Econometric challenges require identifying assumptions to model the within-teacher returns to experience with teacher fixed effects. We describe the identifying assumptions used in past models and in a new approach that we propose, and we demonstrate how violations of these assumptions can lead to substantial bias. Consistent with past research, we find that teachers experience rapid productivity improvement early in their careers. However, we also find evidence of returns to experience later in the career, indicating that teachers continue to build human capital beyond these first years.