The prevalence of obesity, a major risk factor for four of the ten leading causes of death (cardiovascular disease, diabetes, dietary cancers, and stroke), has risen dramatically over the past 20 years in the United States. In neighborhoods with few economic resources, aspects of the built environment may be less conducive to physical activity and healthy diets, placing residents disproportionately at risk. The growing health burden of obesity and co-morbidities highlight the need to identify effective measures of the means by which the built environment influences health, as well as effective interventions to create healthier environments. The longitudinal study proposed here will contribute to both of these goals. Specifically, the proposed initiative is to: 1) Assess independent and collective scientific contributions of five methods of assessing characteristics of the built environment (measures of accessibility; mapping; typologies of neighborhood characteristics; observation; and residents' perceptions) for understanding the means by which the built environment influences behavioral and biological factors associated with obesity and related co-morbidities among African American, Hispanic and white residents of Detroit; 2) Develop and implement additional components of a multilevel, multi-site intervention that incorporates modifications of the built environment and that builds on ongoing social and behavioral approaches to promote physical activity and access to healthy foods in eastside, northwest and southwest Detroit; 3) Conduct longitudinal analyses to evaluate the independent and cumulative effects of modifications of the built environment, alone and in conjunction with multilevel, multi-site social, informational and behavioral approaches to promote physical activity and access to healthy foods among African American, Hispanic and white residents of eastside, northwest and southwest Detroit; and 4) Disseminate knowledge gained about the implications of changes in the built environment alone, and in conjunction with behavioral and social interventions, for behavioral and biological indicators of obesity and related co-morbidities to community members and to local, regional and national decision makers.