This report presents results of a randomized trial of a state prekindergarten program. Low-income children (N = 2990) applying to oversubscribed programs were randomly assigned to receive offers of admission or remain on a waiting list. Data from pre-k through 3rd grade were obtained from state education records; additional data were collected for a subset of children with parental consent (N = 1076). At the end of pre-k, pre-k participants in the consented subsample performed better than control children on a battery of achievement tests, with non-native English speakers and children scoring lowest at baseline showing the greatest gains. During the kindergarten year and thereafter, the control children caught up with the pre-k participants on those tests and generally surpassed them. Similar results appeared on the 3rd grade state achievement tests for the full randomized sample – pre-k participants did not perform as well as the control children. Teacher ratings of classroom behavior did not favor either group overall, though some negative treatment effects were seen in 1st and 2nd grade. There were differential positive pre-k effects for male and Black children on a few ratings and on attendance. Pre-k participants had lower retention rates in kindergarten that did not persist, and higher rates of school rule violations in later grades. Many pre-k participants received special education designations that remained through later years, creating higher rates than for control children. Issues raised by these findings and implications for pre-k policy are discussed.