"More couples are sharing family tasks than ever before, and the movement toward sharing has been especially significant for full-time dual-earner couples," the report says. "Men and women may not be fully equal yet, but the rules of the game have been profoundly and irreversibly changed."
Some couples have forged partnerships they consider fully equitable.
"We'll both talk about how we're so lucky to have someone who does more than their share," said Mary Melchoir, a Washington-based fundraiser for the National Organization for Women, who — like her lawyer husband — works full-time while raising 6-year-old triplets.
"He's the one who makes breakfast and folds the laundry," said Melchoir, 47. "I'm the one who fixes things around the house."
Joshua Coleman, a San Francisco-area psychologist and author of "The Lazy Husband: How to Get Men to Do More Parenting and Housework," said equitable sharing of housework can lead to a happier marriage and more frequent sex.
"If a guy does housework, it looks to the woman like he really cares about her — he's not treating her like a servant," said Coleman, who is affiliated with the Council on Contemporary Families. "And if a woman feels stressed out because the house is a mess and the guy's sitting on the couch while she's vacuuming, that's not going to put her in the mood."
The report's co-authors, sociologists Scott Coltrane of the University of California, Riverside and Oriel Sullivan of Ben Gurion University, said they were addressing a perception that women's gains in the workplace were not being matched by gains at home.
"The typical punch line of many news stories has been that even though women are working longer hours on the job and cutting back their own housework, men are not picking up the slack," Coltrane and Sullivan wrote.
They said this perception was based on unrealistic expectations and underestimated the degree of change "going on behind the scenes" since the 1960s. The change, they said, "is too great a break from the past to be dismissed as a slow and grudging evolution."
Among the findings they cited:
—In the U.S., time-use diary studies show that since the '60s, men's contribution to housework doubled from about 15 percent to more than 30 percent of the total. Over the same period, the average working mother reduced her weekly housework load by two hours.
—Between 1965 and 2003, men tripled the amount of time they spent on child care. During the same period, women also increased the time spent with their children, suggesting mutual interest in a more hands-on approach to child-raising.
Sullivan and Coltrane predict men's contributions will increase further as more women take jobs.
"Men share more family work if their female partners are employed more hours, earn more money and have spent more years in education," they said.
Pamela Smock, a University of Michigan sociologist who also works with the council, said a persistent gender gap remains for what she called "invisible" household work — scheduling children's medical appointments, buying the gifts they take to birthday parties, arranging holiday gatherings, for example.
Marriage equality is more elusive among blacks than whites, with black women shouldering a relatively higher burden in terms of child care and housework, said council collaborator Shirley Hill, a sociology professor at the University of Kansas.
The report's overall findings meshed with what Carol Evans, founder and CEO of Working Mother magazine, has been observing as she tracks America's two-income couples.
"There's a generational shift that's quite strong," she said. "The younger set of dads have their own expectations about themselves as to being helpful and participatory. They haven't quite gotten to equality in any sense that a women would say, 'Wow, that's equal,' but they've gotten so much farther down the road."