The authors review epidemiological and survey research relevant to the relationships between religiousness/spirituality and mental health in people at the end of life, with the end of helping psychiatrists, psychologists, and other mental health professionals dealing with older Americans. They give special attention to well-being, religious coping, cognitive dysfunction, anxiety, depression, and suicide, and consider the extent to which hope is a mediator of the purported salutary effects of religiousness. Studies were selected from the comprehensive and systematic review of 20th-century scientific literature concerning religion and health. Authors also review current studies relevant to religion and end-of-life issues. Religious persons reported generally higher levels of well-being. The review also found fairly consistent inverse associations of religiousness with rates of depression and suicide. There was some negative association between religious participation and cognitive dysfunction, but the association with anxiety was inconsistent, with some studies showing a correlation between higher levels of religion and anxiety. Religion's effects on mental health are generally protective in direction but modest in strength.Public opinion polls suggest that the United States is a very religious nation. The 1999 Gallup Poll reports that 94% of Americans believe in God or a higher power; an almost equal proportion of the population says that religion is very or fairly important in their lives. 1 Less than a majority of these respondents report weekly attendance at religious services, but American rates of religious service attendance are still higher than for almost all other developed countries. 2 Most Americans believe that religion and health are intimately related. A 1996 Time/CNN poll conducted by Yankelovich Partners reports that 77% of respondents believe that God sometimes intervenes to cure people who have serious illnesses. 3 Furthermore, people act upon such beliefs. This same poll reports that 82% of Americans profess belief in the healing power of prayer. Also, research by Eisenberg and colleagues 4 shows that Americans spend billions of dollars annually on "alternative" medical therapies, and many of these therapies have spiritual meanings associated with them. 4,5