As state-funded pre-kindergarten (pre-K) programs expand, it is critical to investigate their short- and long-term effects. This article presents the results through sixth grade of a longitudinal randomized control study of the effects of a scaled-up, state-supported pre-K program. The analytic sample includes 2,990 children from low-income families who applied to oversubscribed pre-K program sites across the state and were randomly assigned to offers of admission or a wait list control. Data through sixth grade from state education records showed that the children randomly assigned to attend pre-K had lower state achievement test scores in third through sixth grades than control children, with the strongest negative effects in sixth grade. A negative effect was also found for disciplinary infractions, attendance, and receipt of special education services, with null effects on retention. The implications of these findings for pre-K policies and practices are discussed.