Forty percent of all Americans meet regularly in support groups such as AA or Bible Study. Princeton's chronicler of religious life Wuthnow (Christianity in the Twenty-first Century, Acts of Compassion) interviews 1,000 support-group members to find out why -- and comes up with some intriguing conclusions in this thoughtful, well-written work. Most Americans, Wuthnow claims, lead lives not of quiet desperation but of turbulent upheaval; the average family moves at least once every three years, and half of those families are ripped apart by divorce. Many people -- like 26-year-old mother-of-two Karen, whose parents divorced and remarried while she was still in high school, who has herself changed jobs 6 times and moved 11 times in the past 12 years -- look to small groups (Karen belongs to a women's Bible Study group that meets once a week) to provide a sense of family and community. But while support groups can be many things to many people -- helping members become more spiritually disciplined, building self-esteem, and providing forums for the narration of individual stories -- such groups are no substitute for the multi-textured ties that families create over decades in the dailiness of private life. Nor, posits Wuthnow, can support groups be expected to eliminate crime and poverty, create jobs, recast foreign policy, or reduce the national debt. Still, these gatherings -- many take place in church basements -- are clearly one of the most vital forces in American ecclesiastical life; in fact, the traditional Sunday morning churchgoer may well be replaced by the Monday or Wednesday evening support-group member. Sensitive, well-reasoned, and insightful -- with valuable commentary on the much-maligned ""culture of victimhood.