Later school start times have emerged as a potential policy to improve the sleep and educational outcomes of teenagers. This study uses a quasi-experimental comparative interrupted time series approach to examine a 90-min delay in start times in an urban district in North Carolina. Results show that the later start time resulted in more sleep for students and improved course grades but limited evidence of benefits to other educational outcomes. In addition, the evidence suggests that disruptions from the change may temporarily decrease some educational outcomes, and that these disruption effects are concentrated among low-income students and students of color.