The types of environments that affect behavior may be physical (e.g., weather or climate, community resources, the built environment, the information environment) or social (e.g., social support, norms, beliefs, and attitudes) as well as objective (actual) or subjective (perceived) (Sallis & Owen, 2002). The environment can be a particularly strong behavioral determinant for behaviors that are directly shaped through environmental constraints and supports, such as physical activity (Owen et al., 2004; Bandura, 1986). This entry focuses mainly on the built environment related to eating and physical activity. The final two sections present brief overviews of tobacco control environments and alcohol environments, two other major public health issues in which ‘environments’ have been the focus of study in recent years.