The Unexpected Legacy of Divorce. By Judith S. Wallerstein, Julia M. Lewis and Sandra Blakeslee. Hyperion, 316 pp., $24.95.

ANYONE WHO NEEDS more evidence that divorce harms children should examine Judith Wallerstein's book, written with her colleague Julia M. Lewis and science writer Sandra Blakeslee. Her 25-year follow-up study of 131 children whose parents divorced in the early '70s convinced her that "the major impact of divorce does not occur during childhood or adolescence. Rather, it rises in adulthood as serious romantic relationships move to center stage." Wallerstein presents her findings through the stories of seven children, five from families of divorce and two from troubled intact families. These detailed--and representative--case histories are interspersed with vignettes of other families, statistics, analysis and comment.

Wallerstein begins by contrasting the lives of Karen and Gary, two children of moderately unhappy marriages. One set of parents divorced, the other stayed together. The history of children such as these leads to one of Wallerstein's main conclusions: If a marriage is not so explosive or chaotic or unsafe that husband and wife find living together intolerable, they should seriously consider staying together for the sake of their children. "If a couple can maintain their loving, shared parenting without feeling martyred," assuring the benefits of the marriage for their children is worth bearing their unhappiness with each other.

The depth of her knowledge of the families she discusses and her sympathy with the parents as well as the children make Wallerstein's conclusions convincing. In discussing the divorce of Karen's parents, she shows how often divorce is precipitated by factors outside the marriage, such as the death of a parent, loss of a job, or serious illness of a child. If spouses who turn to one another for comfort fail to find kindness or tenderness, their anger may lead to an impulsive end to the marriage.