Understanding the environmental determinants of physical activity in populations at high risk of inactivity could contribute to the development of effective interventions. Socioecological models of activity propose that environmental factors have independent and interactive effects of physical activity but there is a lack of research into interactive effects. This study aimed to explore independent and interactive effects of social and physical environmental factors on self-reported physical activity in income-deprived communities. Participants were 5,923 adults in Glasgow, United Kingdom. Features of the social environment were self-reported. Quality of the physical environment was objectively-measured. Neighbourhood walking and participation in moderate physical activity MPA on ≥5 days/week was self-reported. Multilevel multivariate logistic regression models tested independent and interactive effects of environmental factors on activity. 'Social support' (walking: OR:1.22,95%CI = 1.06-1.41,p<0.01; MPA: OR:0.79,95%CI = 0.67-0.94,p<0.01), 'social interaction' (walking: OR:1.25,95%CI = 1.10-1.42,p<0.01; MPA: OR:6.16,95%CI = 5.14-7.37,p<0.001) and 'cohesion and safety' (walking: OR:1.78,95%CI = 1.56-2.03,p<0.001; MPA: OR:1.93,95%CI = 1.65-2.27,p<0.001), but not 'trust and empowerment', had independent effects on physical activity. 'Aesthetics of built form' (OR:1.47,95%CI = 1.22-1.77,p<0.001) and 'aesthetics and maintenance of open space' (OR:1.32, 95%CI = 1.13-1.54,p<0.01) were related to walking. 'Physical disorder' (OR:1.63,95%CI = 1.31-2.03,p<0.001) had an independent effect on MPA. Interactive effects of social and physical factors on walking and MPA were revealed. Findings suggest that intervening to create activity-supportive environments in deprived communities may be most effective when simultaneously targeting the social and physical neighbourhood environment.