We tested a social cognitive model of physical activity (PA) in the cultural context of the Czech Republic, a postcommunist central European country. In total, 546 older Czech adults (mean age = 68 years, data collected in 2013) completed a battery of questionnaires assessing indicators of PA and related social cognitive constructs, including self-efficacy, social support, and self-regulation strategies. Subsequently, a structural equation model was used to test the relationship between the social cognitive constructs and PA. Our analyses indicated an acceptable fit of the proposed model (CFI = .911; SRMR = .046; RMSEA = .073). Self-regulation was predicted by self-efficacy (β = .67) and social support (β = .23), which predicted PA (β = .45). The model explained 60.4% of the variance in PA self-regulation and 20.5% of the variance in PA participation. The results provide further evidence for the role of self-efficacy and social support in enabling PA in older adults, and suggest that this relationship is partially mediated by self-regulation.