<p>Religious participation may be protective against social isolation, which itself is a risk factor for poor health outcomes in aging adults. Research extending back to Durkheim’s work on religion and suicide, and frameworks such as Stryker and Statham’s Interactional Role Theory, link religion to social integration, which is the opposite of social isolation. However, little empirical research has examined the association between religious participation and social isolation in middle-aged and older adults. We investigated this association using two waves of data (n = 22,139) from the Comprehensive Cohort of the Canadian Longitudinal Study on Aging. We regressed follow-up social isolation onto baseline religious participation and controlled for a series of socio-demographic, health, and social connection variables at baseline. Social isolation was measured using an index aggregating social network size, frequency of contact with network members, social activity participation, marital status, and retirement status. Religious participation was measured using a three-level variable asking about the frequency of participation in religious activities over the past year. Religious participation was not statistically significantly associated with social isolation over three years of follow-up. Among populations that experience healthier aging, our results did not show an association between religious participation and social isolation. Future research warrants longer follow-ups in less healthy populations to further investigate the association.</p>