Childhood obesity rates in the United States are growing, especially among African American children.  Without a comprehensive understanding of the numerous environmental factors that influence physical activity, rising rates cannot be effectively curbed.  This dissertation study evaluated the direct and indirect effects of personal factors, built environment, and social environmental factors on African American adolescents' body mass index (BMI) and how the relationships can be affected by physical activity in an urban setting in Baltimore City, MD.  Physical activity was assessed in three environments: residential, commercial, and recreation.  This study leveraged funds by using data collected in another Active Living Research funded study (Carolyn Voorhees) and expanded the research to examine the complex environmental features that encourage sedentary behaviors and discourage physical activity in an urban setting.  From data collected, statistical analysis was used to determine if environmental factors affect BMI in the study population.