YOU MAY remember the old joke about the elderly couple who come into a lawyer's office to arrange their divorce after 60-plus years of marriage. After learning that the aged duo are indeed serious and want only to be rid of each other, the lawyer says, "Pardon my asking, but if you guys are so unhappy with each other, why didn't you come to see me sooner?"

Their reply: "We wanted to wait until the children died."

Despite its gruesomeness, this gag usually gets a good laugh. But for some -- the children of divorce -- the laugh is bittersweet. The unhappy truth that emerges from the latest research is that in the long run, divorce is beneficial for the mismatched spouses, but intensely disturbing to the kids. For them, our soaring divorce rates are little comfort. In 1960, the number of marriages in the U.S. outnumbered divorces by nearly four to one; by 1970 it was three to one, by 1980 only two to one. The persistence of the divorce boom has enabled scientists to complete a substantial volume of research on the effects of divorce on children, including several long-term projects tracking their subjects into adulthood. Results vary by group, sex and age. But it now seems clear that:

The effects of divorce on kids, ranging from the mild to the disabling, last much longer than psychologists anticipated; and

Negative effects can be muted, and children can survive with healthier psyches, if the parents keep their hostilities under control, pay attention to their kids, and generally refrain from behaving like jerks.

Researchers have ceased to study divorce as a discrete event but see it rather as a complex process that starts before the actual separation and continues through successive disruptions: changes in residence and economic status; loss of the non-resident parent; adjustment to parental dating; remarriage and the introduction of stepfamilies and sometimes half-siblings.

Meanwhile, access to the custodial parent -- usually the mother -- is curtailed as she goes back to school or to work, is disabled by her own depression, alcohol use or despair, and reactivates (in many cases frenetically) her social life.

"For kids, the misery their parents may feel in an unhappy marriage is usually less significant than the changes {the children} have to go through after a divorce," says Neil Kalter, a psychologist at the University of Michigan who has spent several years developing support groups in public schools for children of divorce. "They'd rather their parents keep fighting and not get divorced."

The first two years following separation are generally considered the crisis period. Unfortunately, this is often the time at which the parents, preoccupied and consumed with their own life changes, are least able to help their children. These effects go on for years as the child continues to react, his family circumstances combining with the normal difficulties of growing up.

Judith Wallerstein and Joan Berlin Kelly, authors of the seminal work "Surviving the Break Up: How Parents and Children Cope with Divorce," found that few of the kids in their follow-up survey agreed with their parents' decision to divorce -- even five years after the parents separated. (These results are part of the researchers' continuing study of 144 middle- and upper-middle class California children of divorce.) In a 10-year follow-up, published last month in the American Journal of Psychiatry, Wallerstein reported that among the 38 young people in the original study who were between 6 and 8 at the time their parents split, over half later viewed the divorce as "the central experience in their lives." A majority expressed "feelings of sadness or neediness, of a sense of their vulnerability," and were "burdened by intense worries about failure in present and future relationships . . . and by an overall sense of their own powerlessness."

As the Twig Is Bent

Several researchers have found that although divorce has no discernible influence on a child's academic achievement, it does affect his social and mental health. In a national survey of 699 children, John Guidabaldi of Kent State University and Joseph D. Perry of Tod Babies' and Children's Hospital (Youngstown, Ohio) found that children of divorced parents performed worse than children of intact families on 9 of 30 mental-health measures, showing more dependency, more irrelevant talk, withdrawal, blaming, inattention, decreased work effort and unhappiness. Several researchers have observed that children of divorce are over-represented among patients at mental health clinics.

Boys and girls, it seems, react to divorce in significantly different ways.

Mavis Hetherington of the University of Virginia, who surveyed 144 middle-class white children over a six-year period, found that in general divorce has more long-term effects on boys than girls, although girls have more problems with a mother's remarriage. She also found, in a study of girls between 13 and 17, that they sought attention from males more often than girls from intact or widowed families, had less self-esteem, and were more likely to be sexually active. Guidobaldi and Perry found that boys fared somewhat less well than girls in the mental-health measures.

Wallerstein and Kelly also noted a variety of sex differences. Girls whose mothers took the initiative in getting divorced coped better than their brothers. Eighteen months after the separation, they found that more boys than girls were still opposed to the divorce, more longed for their father, more felt rejected by him, and more were depressed. Boys between 9 and 12 at the time of the divorce were more likely to be angry (as opposed to depressed or withdrawn) and to retain that anger.

Girls, however, were more likely to be concerned about the family's economic situation, and were more likely to do well in school if they felt financially secure. Boys whose mothers did not work full-time were more likely to do well in school. However, girls often had delayed reactions to the divorce; these appeared when they hit the mine-field of adolescence. In her 10-year follow-up study, Wallerstein found that out of 38 subjects, five had dropped out of high school -- all of them girls. Of the 24 young women in the sample, 8 (33 percent) had gotten pregnant out of wedlock and four had had at least one abortion; two had second abortions. Sixteen had a history of mild delinquency (usually drinking or drug use). Male misbehavior, however, was more serious: Four of 14 boys had been arrested more than once and two had served time in jail.

A "significant minority" of the girls expresed their insecurity, anger or lack of self-esteem in promiscuous sexual behavior, some deliberately gravitating to older men or a series of aimless relationships. One 20-year-old said, "I've had no limits and no control. I'm prepared for anything. I don't expect a lot. I just want to stay alive. Love is a strange idea to me. Life is a chess game. I've always been a pawn."

Kalter also found a higher rate of sexual activity, substance abuse and running away among adolescent girls, especially when the divorce occurred before elementary school and the father had departed. Other studies show that female children of divorced parents are more likely to have marital problems of their own, more likely to choose "inadequate husbands" and to be pregnant at their weddings.

Their Fathers' Daughters

Another survey of 40 white, middle-class midwestern girls in third and sixth grades found few academic differences between those whose parents had been divorced and those from intact families. But third graders scored distinctly lower than their intact-family counterparts on social and physical competence scales. These differences were not found among the sixth graders, however -- perhaps, the researchers speculate, because the divorce is a relatively more recent event in the lives of the younger group.

A study of 84 women -- half of them children of divorce -- at an exclusive private college found that there was no dissimilarity in the two groups' academic achievements. The main difference was in their perception of masculinity and femininity: The "D" group girls were more prone to see men as unfeeling and weak, and women as insensitive and immature, than were the "I" (for intact) group. The D group members also felt less certain about their own chances of having a lasting marriage.

One theme that consistently and strikingly emerges from research on divorce and children is the significance of the father. Historically fathers have tended to downgrade their importance in their child's development, especially during the early years, but research into the effects of divorce shows this notion to be a myth. Whether the child be girl or boy, preschooler or adolescent or pre-pubescent, Dad's present behavior or absent neglect produces enduring psychic ramifications.

Even when a father has been undeniably rotten, children long for his presence and attention. The disruption of the relationship with a loving, attentive father is brutal, as the child perceives that the man who adored him has now left him flat. A good father can ameliorate the effects of a dysfunctioning custodial mother and augment the impact of a good one; even a less competent father provides a link that children seem desperately to need.

Wallerstein and Kelly describe a "passionate, persistent yearning of the children" for the father, especially in those 8 years old and younger. Although children will sometimes say they don't want to visit their father (in order to avoid fights between their parents), only 11 percent of the children in the study were either genuinely reluctant to see him or relieved that the presence of an overbearing, cruel or domineering father was removed from their lives.

Eighteen months after the divorce, children perceive the father with less respect; and half of the 9-to-12-year-old boys openly rejected him as role model. But by the five-year mark, there was a clear correlation between the health of the relationship with the father and the child's attitude toward the divorce: Those who still felt the divorce had been a mistake (approximately 28 percent) had a bad relationship with the custodial mother or yearned for their father. Boys between 9 and 13 expressed particular longing for their fathers and worried that their own masculinity was in jeopardy without a role model. However, the survey also found that while the children who were still depressed five years after the divorce generally had neglectful fathers, a caring and involved father was no talisman against gloom, especially if the mother was inadequate.

(Although 85 percent of the fathers in Wallerstein's study of relatively affluent professionals paid child support, a surprising number refused to help pay for college. Partly as a result, only 66 percent of the eligible children in the study were attending or had graduated from college at the time of the 10-year follow-up, although 85 percent of the high-school graduates in the community went on to a higher education.)

Feeling and Failure

Inevitably, the conduct of the parents is crucial to the outcome. If a separated couple maintains "mutual respect and minimal hostility, empathetic awareness of children's needs to feel loved and valued, and {the} father's continued involvement," then children can emerge from the divorce without major psychic damage. They may even demonstrate greater maturity, independence and empathy for others as a result of their own experiences. Unfortunately this situation is all too rare. Most parents forget, or are unaware, that children often interpret parental trauma as rejection. And as Wallerstein and Kelly note, "children cannot mark time for an extended period while parents integrate their own lives."

Megan Rosenfeld is a Washington Post staff writer.