How Does a Four-Day School Week Affect High School Students? Evidence from Colorado
We examine the impact of the four-day school week on high school students’ outcomes using comprehensive administrative data from Colorado, the state with the highest prevalence of this schedule in the United States. The dataset spans nearly two decades of entry cohorts and more than one million unique student records, providing an exceptional opportunity to study the policy’s long-run effects. Leveraging quasi-random variation in adoption across districts within a difference-in-differences framework, we estimate how a shortened school week shapes stu-dents’ educational trajectories. In contrast to much of the existing literature, we find modest improvements in standardized test performance, lower dropout rates, and higher on-time and overall graduation. The duration of exposure plays a key role: students with longer and consis-tent exposure experience the largest improvements in persistence and attainment. At the same time, heterogeneous effects indicate that disadvantaged groups may benefit less, raising con-cerns about equity. Overall, the findings challenge the perception that a shorter school week harms student learning and suggest that, when designed and implemented carefully, it can en-hance both performance and completion