This study takes advantage of a large, existing database of physical activity measurements collected from sixth and seventh graders in ten Massachusetts schools. The purpose is to see if their physical environment at school or in the neighborhood affects the children’s activity levels. The data includes active and sedentary periods by time of day for 251 students in ten neighborhoods, measured by accelerometer and diaries. The University of North Carolina researchers are evaluating neighborhood features, such as density, mix of uses, and completeness of the sidewalk network, using GIS data, aerial photographic maps, and site visits. The same is being done for the children’s schools, which includes collection of data about traits such as the size of the campus and the presence of stairs. Among the questions Cradock’s team will be asking is if the pedestrian environment in the neighborhood is related to physical activity for students on weekends, and if “active-school environments” are associated with more activity during the school day. The database also includes information about weather conditions; the researchers will see if the neighborhood environment influences the choices of children to walk or bike in varying weather conditions.