The study examines the impact of the US Environmental Protection Agency’s (EPA) 2012-2017 School Bus Rebate Program funding on school attendance. The program aimed to hasten the transition of school bus fleets to cleaner vehicles to reduce the adverse health impacts of diesel exhaust on students. The study found that districts randomly selected for funding had greater attendance improvements than unselected districts after the lottery, resulting in over 350,000 estimated additional student days of attendance each year. Attendance improvements were greatest when the oldest buses were replaced and for districts with high ridership on applicant buses. The study concludes that increasing the pace of replacing older, highly polluting buses positively impacts student attendance, and replacing all pre-2000 model year school buses could lead to over 1.3 million additional student days of attendance per year.