2020 The Author(s). Background: Social capital is a collective attribute of communities that determines health and well-being of populations. The collective resources in a high social capital community have been reported to result in better health outcomes. While evidence supports the links between social capital and various health outcomes, it is not clear about underlying mechanisms connecting multiple dimensions of social capital to health. Methods: Using the two-wave data from a nationally representative cohort study of Australian adults (N = 16,637), this study examined the effects of two dimensions of social capital (i.e., structural and cognitive social capital) on physical and mental health in the Australian adult population. Based on prior literature and theoretical reasoning, it was anticipated that the structural and cognitive social capital would influence self-assessed health status (physical and mental health). Additionally, these two dimensions of social capital were hypothesized to moderate the relationships between chronic health conditions and these two aspects of health status. Results: Analyses showed that the effects of chronic health conditions on mental health status were moderated by the structural social capital (β =.652, SE =.249, p =.009). Additionally, it was found that perceived community cohesion was predictive of mental health (β =.295, SE =.103, p =.004). Our analysis also indicated that perceptions of disadvantaged neighbourhood environment contributed to poorer mental health status (β = -.461, SE =.144, p =.001). However, none of the social capital variables significantly predicted physical health status. Conclusions: Findings suggest that the structural dimension of social capital would function as a buffer against the malicious effects of chronic health conditions, impairments and disabilities. Specifically, community participation (structural social capital) is indispensable to develop an effective community-based program to improve health and well-being of those with chronic health conditions or disabilities, as increasing active participation may generate beneficial effects in this vulnerable population. Subjective perceptions about communities can also play an important role in improving better health outcomes. Further research is needed to examine underlying mechanisms linking the multiple dimensions of social capital to health outcomes among individuals who are vulnerable to external stressors.