This report details findings of the Cost, Quality, and Outcomes (CQO) Study, which examined the influence of typical center-based childcare on children's development during their preschool years and then subsequently as they moved into elementary school. Among the major findings of the study are that children who attended higher quality childcare centers scored higher on cognitive and social skills measures in childcare and through the transition into school. This influence of childcare quality was important for children from a wide range of family backgrounds. Childcare quality prior to school entry affected children's development at least through kindergarten. For math skills and problem behaviors, children whose mothers had lower levels of education benefited even more from high quality childcare, with these influences sustained through second grade. The quality of childcare classroom practices was related to children's cognitive development, while the closeness of the caregiver-child relationship influenced children's social development through the early school years. The report concludes with discussion of implications for practice and policy, focusing on fiscal strategies, system and program change strategies, and professional preparation and compensation approaches. (KB)