BACKGROUND Research regarding the pathways via which the environment influences physical activity is limited. This study examined the role of perceived behavioral control (PBC) in mediating the relationship between perceptions of neighborhood walkability and frequency of moderate (MODPA) and vigorous physical activity (VIGPA). METHODS Data were collected through a province-wide survey of physical activity. Telephone-interviews were conducted with 1207 adults and captured information about perceptions of neighborhood walkability, physical activity, PBC and demographics. Gender-stratified regression analyses were conducted to test PBC mediation of the built environment-physical activity association. RESULTS Among women easy access to places for physical activity was positively associated with MODPA and VIGPA. Having many shops and places within walking distance of homes was also positively associated with MODPA among women however; reporting sidewalks on most neighborhood streets, and crime rate in the neighborhood were negatively correlated with MODPA. Among men, easy access to places for physical activity was positively associated and crime rate in the neighborhood negatively associated, with VIGPA. After adjusting for PBC, the association between easy access to places for physical activity and VIGPA and MODPA attenuated for men and women suggesting mediation of this association by PBC. CONCLUSIONS PBC mediated the relationship between easy access to places for physical activity and physical activity, but not for other perceived environmental attributes.