Among the myriad forms of alternative medicine being practiced in the United States, prayer is by far the most popular. More than half of American adults have prayed for better health, and a quarter have participated in prayer groups. Some doctors say that's reason enough to ask patients about their spiritual beliefs, because understanding those beliefs is essential to treating the whole person. But critics argue that probing into personal beliefs is intrusive. However, a majority of the nation's 135 medical schools now teach about spirituality, and many hospitals ask patients about it. Helping to drive this interest is the claim that religion improves your health. But scientific consensus has been reached on only one finding: Regular churchgoers live longer - and that may be because they're healthier than the homebound to start with. Far more controversial are studies claiming that patients heal faster when strangers pray for them. Many experts fault the studies; others say it's impossible to test God with science.

Sarah Glazer specializes in health, education and social-policy issues. Her articles have appeared in The Washington Post, Glamour, The Public Interest and Gender and Work, a book of essays. Glazer covered energy legislation for the Environmental and Energy Study Conference and reported for United Press International. She holds a BA in American history from the University of Chicago.