Previous longitudinal studies have consistently shown an association between attendance at religious services and lower all-cause mortality, but the literature on associations between other measures of religion and spirituality (R/S) and mortality is limited. We followed 36,613 respondents from the Black Women's Health Study from 2005 through December 31, 2013 to assess the associations between R/S and incident all-cause mortality using proportional hazards models. After control for numerous demographic and health covariates, together with other R/S variables, attending religious services several times per week was associated with a substantially lower mortality rate ratio (mortality rate ratio = 0.64, 95% confidence interval: 0.51, 0.80) relative to never attending services. Engaging in prayer several times per day was not associated with mortality after control for demographic and health covariates, but the association trended towards a higher mortality rate ratio when control was made for other R/S variables (for >2 times/day vs. weekly or less, mortality rate ratio = 1.28, 95% confidence interval: 0.99, 1.67; P-trend < 0.01). Religious coping and self-identification as a very religious/spiritual person were associated with lower mortality when adjustment was made only for age, but the association was attenuated when control was made for demographic and health covariates and was almost entirely eliminated when control was made for other R/S variables. The results indicate that service attendance was the strongest R/S predictor of mortality in this cohort.