Obesity is an increasingly important health problem in the United States, particularly among adolescents. Previous studies among adults have shown that people who live in neighborhoods with good "walkability" and recreational environments have increased physical activity levels, and some studies have suggested that there is a relationship between the neighborhood food environment and eating patterns. While these concepts have been studied in adults, more research is needed on the effect of the neighborhood environment on adolescents. In this study, adolescents who live in select neighborhoods in Seattle-King County, WA and Baltimore-Washington, DC will be enrolled. Forty-eight neighborhoods in these areas will be studied, with researchers taking into account the neighborhoods' walkability levels (e.g., combination of street connectivity, residential density, land use mix, retail floor area ratio) and median income levels. Study researchers will examine and create formulas to measure walkability, pedestrian infrastructure, public recreation space, and nutrition environment quality. Researchers will also examine crime and weather patterns; psychosocial variables; parent support; and perceived neighborhood, school, and home environments. Overall, this study will evaluate the ability of a research model to explain the variation in physical activity levels, sedentary behavior, dietary patterns, and weight among adolescents, with an emphasis on neighborhood environment.

There will be no study visits for this study: participation will take place entirely through the mail, phone, or internet. Participants will include adolescents between the ages of 12 and 16 years old and their parents, all of whom live in the identified study neighborhoods. At the time of study entry, adolescents will complete a questionnaire on neighborhood and safety issues, diet, physical activity habits and places where activity occurs, grades, school policies and parental rules that affect physical activity and eating, and the support they get from people regarding healthy eating and physical activity. One parent of each adolescent will also complete a neighborhood information questionnaire. Adolescents will measure their height, weight, and waist circumference and send the measurements to study staff along with the questionnaire. Next, a 4-week period, study staff will call adolescents on three random days and collect information on their diet in the previous 24 hours. During this period, adolescents will wear an activity meter and a GPS monitor for 7 consecutive days and will mail the devices to study staff for analysis.