Resources and Student Achievement—Evidence from a Swedish Policy Reform*

A policy change is used to estimate the effect of teacher density on student performance. We find that an increase in teacher density has a positive effect on student achievement. The baseline estimate—obtained by using the grade‐point average as the outcome variable—implies that resource increases corresponding to the class‐size reduction in the STAR experiment (a reduction of seven students) improves performance by 2.6 percentile ranks (or 0.08 standard deviations). When we used test‐score data for men, potentially a more objective measure of student performance, the effect of resources appears to be twice as large.