Objectives: To test the pathways between perceptions of built environment factors and physical activity in urban youth. Methods: Three hundred fifty high school students' perceptions of neighborhood, and barrier self efficacy were measured by a Web survey. Physical activities were assessed using a one-week diary and accelerometers. Results: Land-use mix/accessibility and neighborhood satisfaction had direct pathways to walking. Barrier self-efficacy had a direct pathway to walking. In addition, land use, specifically neighborhood accessibility, influenced adolescents' walking behavior via self-efficacy. Similar pathways were found in MVPA models. Conclusions: Neighborhood factors appear to work together with self-efficacy to facilitate physical activity.