Using Bandura’s Social Cognitive Theory (SCT) as a framework, this study employed a correlational design to examine the predictive strengths of self-efficacy, exercise goal-setting, exercise planning and scheduling, family social support and friends social support on physical activity behaviours in college students. Additionally, associations between physical activity, income, subjective social status in the community and subjective social status in Ireland were assessed through online surveys. The SCT model predicted 14% of the variance in physical activity, with exercise goal-setting ( = .404) and family social support (=.293) emerging as the strongest predictors. Findings indicated males reported higher levels of physical activity and self-efficacy than females. Results revealed no significant association between SSS in the community, SSS in Ireland, income and physical activity. The present results enhance our understanding of the underlying mechanisms that lead college students to adopt an active lifestyle. Implications for future interventions are discussed.