This study examines the impact on student achievement of implementing management training for principals in traditional public schools in Houston, Texas, using a school-level randomized field experiment. Across two years, principals were provided 300 hours of training on lesson planning, data-driven instruction, and teacher observation and coaching. The findings show that offering management training to principals significantly increases student achievement in all subjects in year one and has an insignificant effect in year two. We argue that the results in year two are driven by principal turnover, coupled with the cumulative nature of the training. Schools with principals who are predicted to remain in their positions for both years of the experiment demonstrate large treatment effects in both years – particularly those with principals who are also predicted to implement the training with high fidelity – while those with principals that are predicted to leave have statistically insignificant effects in each year of treatment.