Measures of religiosity are linked to health outcomes, possibly indicating mediating effects of associated psychological and social factors. We examined cross-sectional data from 92,539 postmenopausal participants of the Women's Health Initiative Observational Study who responded to questions on religious service attendance, psychological characteristics, and social support domains. We present odds ratios from multiple logistic regressions controlling for covariates. Women attending services weekly during the past month, compared with those not attending at all in the past month, were less likely to be depressed [OR = 0.78; CI = 0.74-0.83] or characterized by cynical hostility [OR = 0.94; CI = 0.90-0.98], and more likely to be optimistic [OR = 1.22; CI = 1.17-1.26]. They were also more likely to report overall positive social support [OR = 1.28; CI = 1.24-1.33], as well as social support of four subtypes (emotional/informational support, affection support, tangible support, and positive social interaction), and were less likely to report social strain [OR = 0.91; CI = 0.88-0.94]. However, those attending more or less than weekly were not less likely to be characterized by cynical hostility, nor were they less likely to report social strain, compared to those not attending during the past month.