The purpose of this project was to examine the effect of various neighborhood environmental characteristics, such as access to recreational facilities, community design, and safety, on obesity outcomes among children and adolescents by different geographic units (e.g. census tract, census block group, street network buffer) in a sample largely comprised of racial/ethnic minorities. Data came from two datasets - one providing longitudinal family and neighborhood environmental data and the other providing objective physical activity measurements collected from children in after-school programs. Geographic Information Systems (GIS) data layers were added to the multilevel analysis to provide information on the children's neighborhood environments. Outcome variables for this research project included sedentary behavior and objectively measured physical activity levels.