It wasn't that long ago that house mothers vetted male visitors in the "beau room" of sororities and all-female residence halls. Then came coed dorms, coed floors and even coed restrooms, where horrified parents who stopped to powder their noses on dormitory move-in day discovered urinals next to the tampon dispensers.

How much further, they wondered, could this go?

Welcome to the 21st century, where the newest trend in college living is coed dorms — not by floor, by room.

Stanford University will allow male and female friends to share dorm rooms this fall. So will UC Santa Cruz. Harvard is considering it for 2009. And it's old news at Brown, Dartmouth, UC Riverside and more than 20 other universities, where upperclassmen have been able to request coed living quarters for several years. It may not raise eyebrows among seasoned collegians, but it's taken more than a few new families by surprise.

Moraga dad Randy Shepard was on a tour of Colorado College with his son earlier this year when a student tour guide mentioned the coed option in passing.

"Initially? Shock!" says Shepard. "I mean, we've gone from coed dorms — boys on one floor, girls on another, which was never around in my day — to coed floors. Now they've gone to coed rooms. I don't know where it goes from here."

While Shepard reeled at the entire concept, his son Trevor, a Campolindo senior, worried about more mundane details. How do you get dressed, he wondered?

The coed room option initially arose from concerns about the comfort and safety of gay and transgender students on campus, but now the trend has spread to include heterosexuals who just want to room with a friend.

Some schools offer "gender neutral housing" on a case-by-case basis, others include it in the roommate options for all upperclassmen, so students don't have to be — in the words of the Dartmouth housing office — "limited by the traditional gender binary."

Parents may fret, but to students it's no big deal. Most have close friends of the opposite sex. Many have been to post-prom, coed sleepovers. And they have all watched TV shows such as "Grey's Anatomy," with its houseful of male and female roommates.

Things have changed, says Clayton Valley High graduate Dierdre Ruscitti.

College-age students, ages 18-24, are nearly four times as likely as their older colleagues, ages 55 and up, to have a best friend of the opposite sex, according to a Time magazine study based on a 2002 survey by Synovate and American Demographics. And overall, more than 12 percent of U.S. men say their best buddy was a woman, and 8 percent of women said their best friend was a man.

"There's not as big a gap between genders," says Ruscitti, who just finished her freshman year at the University of Pittsburgh. "A lot of my close friends are male. I would have no problem living with one of them."

Carleton College, a small Minnesota liberal arts college where 90 percent of the students live on campus, is including the coed option in its dorm choices this fall.

"I'm not planning to live with a guy next year," says Carleton sophomore Alexandra Dunn, an alumna of the Athenian School in Danville, "but it's an option we should have. I know that having men and women on the same floor caused a lot of controversy when that first began, so I'd expect this to be controversial as well, and I understand why parents are concerned. "

Proponents say the housing option is designed for platonic friends, not for hooking up. But the latter crops up occasionally — a recent CNN report said students call those hook-ups "roomcest." But everyone seems well aware of the implications of a roommate breakup.

"College students are adults who have the right to make their own decisions about their living situation," says Dunn. "It's already common for students to live in coed off-campus apartments, so I think the choice should logically extend to on-campus dorm rooms."

An increasing number of college officials agree. Coed roommate proposals are under discussion at a number of other campuses, including the University of Chicago and Yale.

So far, the anticipated controversy has failed to materialize. Even Shepard's shock has given way to bemusement. And that male-female privacy question? The Moraga dad figures roommates can always look the other way at appropriate times.

Contact Jackie Burrell at jbur rell@bayareanewsgroup.com.