The age-old stereotype that women do more housework than men has gotten more credibility with a George Mason University study co-written by sociologist Shannon Davis.

The study of more than 17,000 people in 28 countries found that married men report doing less housework than men who are live-in boyfriends.

According to Davis, the key finding of the study is that it suggests the institution of marriage changes the division of labor. Couples with an egalitarian view on gender--seeing men and women as equal--are more likely to divide the household chores equally. However, in married relationships, even if an egalitarian viewpoint is present, men still report doing less housework than their wives.

"Marriage as an institution seems to have a traditionalizing effect on couples--even couples who see men and women as equal," says Davis.

While the researchers did not follow cohabitating couples over time to see if their division of housework changed after marriage, their study provides a "snapshot" in time of couples all over the world.

"Our research suggests that couples across many countries are influenced by similar factors when deciding how to divide the housework," she says. "It's the way the society has defined what being married means, the institution itself, that affects behavior."

This study was recently published in the Journal of Family Issues by Davis and co-authors Theodore Greenstein and Jennifer Gerteisen Marks of North Carolina State University.