This review examines the association between dog ownership and adult physical activity levels. While there is evidence to suggest that dog ownership produces considerable health benefit and provides an important form of social support that encourages dog owners to walk, there is limited evidence on the physical environmental and policy-related factors that affect dog owners walking with their dog. With the high level of dog ownership in many industrialized countries, further exploration of the relationship between dog ownership and physical activity levels may be important for preventing declining levels of physical activity and the associated detrimental health effects.