Since a substantial majority of preschoolers participate in some form of child care before coming to school, the Cost, Quality, and Child Outcomes in Child Care Centers Study (CQO) was designed to examine the influence of typical center-based child care on children's development during their preschool years and as they move into formal elementary education. This report details the results through the end of second grade. Chapter 1 of the report describes the conceptual framework and methods. Measures are summarized related to children's receptive vocabulary, mathematics and letter-word recognition skills, behavior problems, sociability, and peer relationships; parent values and attitudes, and parent involvement; classroom/child care quality; and teacher characteristics. Chapter 2 describes the child care, kindergarten, and second grade classrooms observed, including a discussion of the continuity between child care and school environments. Chapter 3 describes the families of the participating children. Chapter 4 describes the children themselves. Chapter 5 presents the main findings of the study relating child care quality to children's outcomes and discusses their broader importance. Chapter 6 delineates the implications that follow from the findings and makes recommendations for policy and practice. The report concludes by asserting that high quality child care experiences, in terms of both classroom practices and teacher-child relationships, enhance children's abilities to take advantage of the educational opportunities as they enter kindergarten and through the early elementary school years. The report's three appendices contain additional data tables, technical information on measures and data analyses, and lists of papers reporting CQO findings. Contains 52 references. (KB)