The NICHD Study proposes to extend the data collection on approximately 1000 children, ages 8-11, thereby offering an opportunity to expand the study to examine the impact of environmental determinants on selected aspects of middle childhood development. This proposal adds a dimension of a health behavior (physical activity) to the battery of social, emotional, cognitive, linguistic, and health development variables studied over their first seven years of life. Studies of the relationships between psychosocial and educational development, and the development of a health-related behavior are rare if not nonexistent in the literature. The NICHD Study of Early Child Care, when extended to the middle school years, provides an opportunity to simultaneously study the environmental and contextual influences on psychosocial and academic development as well as the determinants of physical activity behaviors. The specific aims of the research are: 1) to determine the antecedents of physical activity in a longitudinal sample of 8- to 11-year-old children; and, 2) to assess relationships between physical activity and other measures of psychosocial, cognitive, and academic development. A proposed measure, BEACHES (Behaviors of Eating and Activity for Children's Health Evaluation System) has been validated as an observation tool. It can be used, within a theoretical framework (social cognitive theory), to examine home and school determinants of physical activity. The detailed analysis of the contextual environment, interactions (prompts and consequences), as well as the interactors' age, gender, ethnicity, and relationships will provide data not available in this age group. The instrument could also be modified to observe behaviors and interactions relevant to a final protocol decided upon by the NICHD Study of Early Child Care Investigators. The results may yield important associations with other key developmental tracking areas related to emotional and physical health. The study is unique because psychosocial and health behavior developmental strands have not previously been woven together in any prospective study of development.