This study addressd previous methodological study limitations by leveraging a unique Obesity and Environment database that comprises the first large scale Geographic Information System (GIS) to link community- and individual-level data in both space and time in a large ethnically diverse population.  The National Lognitudinal Study of Adolescent Health (Add Health), a cohort followed from adolescent to young adulthood, provided extensive individual-level health behavior and outcome data, as well as detailed community-level data such as land use, recreation facilities, economy, climate, and crime data.  These data provided an unprecedented opportunity to examine longitudinal relationships between diverse built environment characteristics and physical activity during adolescence and young adulthood in an ethnically diverse sample.