This article reports data from a 2-year longitudinal study on cooperative learning in school science. The study reported the effects of cooperative learning in science on science attainment, effective development and social connectedness, and interactions during transition from elementary to high school in rural and urban school settings. The project followed 204 children involved a project in cooperative learning in elementary school science and 440 comparison children who were not involved in the elementary school science program as they undertook transition from 24 elementary to 16 high schools. Cognitive, affective, and social gains observed in the elementary school science project survived transition. The implications for improving outcomes in school science during school transition by using cooperative learning initiatives are explored. The implications for practice and policy are discussed. (Contains 2 tables.)