Human engagement with religion and spirituality is pervasive across the world, yet the extent to which religious and/or spiritual involvement promotes well-being is controversial theoretically and empirically. In the largest meta-analysis of religion/spirituality and life satisfaction to date (k = 256, N = 666,085), an overall effect size was computed (r = .18; 95% CI .16-.19; p < .01). Five dimensions of religion/spirituality were then examined separately to gauge their relationships with life satisfaction. Each dimension of religion/spirituality was significantly and positively associated with life satisfaction: religiosity (r = .16, 95% CI .14-.17, p < .01), spirituality (r = .30, 95% CI .25-.35, p < .01), religious attendance (r = .11, 95% CI .09-.13, p < .01), religious practices (r = .14, 95% CI .10-.18, p < .01), and religious/spiritual experiences (r = .29, 95% CI .24-.33, p < .01). The overall effect was moderated by several study-related variables, with a stronger relationship found in samples with higher average age, in more recent studies, in developing nations, and in countries with a higher percentage of people who consider religion very important in their lives. The theoretical and practical implications of the meta-analysis are discussed.