Current research shows that growing numbers of children and adolescents lead sedentary lives and are likely to grow up to be sedentary adults This project will analyze existingdata sets from NICHD’s Study of Early Child Care and Youth Development to examine the physical activity of youth. This secondary analysis will examine physical activity and health in third grade as a predictor of physical activity and health and establishment of physical activity habits in later elementaryand middle school grades.

This study will increase understanding of factors and mechanisms that influence changes in the physical wellbeing of contemporary youth that are associated with forming a habit of physical activity participation. The specific aims of the study are (1) to examine the relation between early profiles of physical activity and the subsequent profiles of physical activity;(2) to model the relation between change in physical activity patterns overtime and children’s health and wellbeing, including BMI, weight-for-height development, body image and general health; and (3) to identify environmental predictors of the development of healthy habits of physical activity and other health outcomes, including parental encouragement, opportunities for physical activity in multiple contexts (PE class, after school activities, organized sports), and competing alternatives (e.g., TV and computer use).The results ofthis study will inform the development of practices within school and out-of-school time settings that support children and adolescents to develop sustained habits of physical activity.