As state-funded prekindergarten programs expand, it is critical to investigate their short- and long-term effects. This paper presents the results through 6th grade of a longitudinal randomized control study of the effects of a scaled-up, state-supported pre-k program. The analytic sample includes 2990 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 6th grade from state education records showed that the children randomly assigned to attend pre-k had lower state achievement test scores in third through 6th grades than control children, with the strongest negative effects in 6th 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. [This paper was published in "Developmental Psychology" v58 n3 p470-484 2022.]