Background: Studies have indicated that there is a positive and indirect relationship between physical activity(PA) and quality of life(QoL). The current study examined this relationship through a social cognitive model with consideration to the intermediary effects of exercise self-efficacy,and physical(PCS, physical component summary) and psychological(MCS, mental component summary) health. Additionally, this model was widened to include concepts from the ecological theory, and any causal associations among neighborhood environment, PA, and QoL.Methods: Six hundred and eighty-four physically active adults(39.16 ± 13.52 years, mean ± SD), living in Athens, Greece, completed a series of questionnaires measuring PA, QoL, exercise self-efficacy, PCS, MCS, neighborhood environment, and family and friend support for PA. The examined models were analyzed using structural equation modeling.Results: The social cognitive and ecological models proved to be of appropriate fit. Within the social cognitive model, PA positively affected QoL through the mediating effects of exercise self-efficacy, PCS, and MCS. With regards to the ecological model, neighborhood environment positively influenced QoL through the intermediary effects of family support for PA, exercise self-efficacy, PA, PCS, and MCS.Conclusion: Results indicated that the most important mediators in the examined models were exercise self-efficacy and health. Further, findings demonstrated the role of neighborhood environment in enhancing PA and QoL. Future studies should be carried out applying longitudinal data for a better understanding of these associations over time. Background: Studies have indicated that there is a positive and indirect relationship between physical activity (PA) and quality of life (QoL). The current study examined this relationship through a social cognitive model with consideration to the intermediary effects of exercise self-efficacy, and the physical (PCS, physical component summary) health. Additionally, this model was widened to include concepts from the ecological theory, and any causal associations among neighborhood environments, PA, and QoL. Methods: Six hundred and eighty-four physically active adults (39.16 ± 13.52 years, mean ± SD), living in Athens, Greece, completed a series of questionnaires measuring PA, QoL, exercise self-efficacy, PCS, MCS, neighborhood environment, and family and friend support for PA. The examined models were analyzed using structural equation modeling. Results: The social cognitive and ecological models proved to be suitable for fit. Within the socia L cognitive model, PA positively affected QoL through the mediating effects of exercise self-efficacy, PCS, and MCS. With regards to the ecological model, neighborhood environment positively influenced QoL through the intermediary effects of family support for PA, exercise self-efficacy, PA, PCS, and MCS.Conclusion: Results indicated that the most important mediators in the examined models were exercise self-efficacy and health. Further, findings demonstrated the role of neighborhood environment in enhancing PA and QoL. Future studies should be carried out longitudinal data for a better understanding of these associations over time.