Once upon a time, the job description for "dad" had only two parts: A father put bread on the table and disciplined the children when they got out of line. If you did those two things, you were a good father. But times change, and now with more than 60 percent of mothers working when their children are older than age 6, the active involvement of fathers in all phases of child rearing is more important than ever, say Notre Dame sociologists Joan Aldous and Gail Mulligan. Their recent study, published in the _Journal of Family Issues_, in fact, offers evidence that fathers who are actively involved in child rearing have a profound positive influence on their children. Analyzing a national sample of white children from stable, two-biological-parent homes, Aldous and Mulligan found that preschoolers with active caregiver fathers were less likely to exhibit behavioral problems later in elementary school. At the same time, difficult preschoolers whose fathers were not much involved were reported to have more behavioral problems in elementary school. The Notre Dame sociologists' research suggests that fathers' care is particularly helpful in heading off behavioral problems among sons. Aldous and Mulligan report that "fathers who take more care of sons seem to establish special relationships with them that positively influence sons' later behavior." Young daughters did not receive the same benefit. The active attention of fathers as well as the comfort they provide can be "an essential source of well-being for children,"Aldous and Mulligan write. "To be effective now, fathers, like good mothers always have been, must be there for their children when they are experiencing personal difficulties. "It is not just providing a good income that good fathering requires, although that is important," they say. "Fathers along with mothers can serve as confidants for troubled children's worries." All this good parenting doesn't come without a cost, however. Aldous and Mulligan report that the more hours a father spends watching over grade-school children, the more depressed he is likely to be. "Child care, it seems, can be discouraging for fathers as well as mothers," they write.