Move over, Ellen DeGeneres, and make way for the younger girls. Way younger, actually, and way different from what most people think of as lesbians.

You can see this new trend on Friday nights outside Union Station, sweethearts from high schools around the Washington area, some locking lips, others hanging out in their tight blue jeans and puffy winter parkas, talking on their cell phones.

You can see them in the hallways of high schools like South Lakes in Reston, Magruder in Rockville or Coolidge in the District. In 2002 at Coolidge, a teacher got so fed up with girls nuzzling each other in class and other public places that he threatened to send any he saw to the principal's office. He admitted to students that he wouldn't report boy-girl kisses, setting off a furor among a student body that, the year before, had chosen a lesbian pair as the school's cutest couple.

These girls pack Ani DiFranco concerts and know tATu lyrics by heart. Their attention is usually directed exclusively at each other but not always: A group of girls at a private school in Northwest Washington charge boys $10 to watch the girls make out in front of them. At one school dance earlier last year, a chaperon had to break up a group of guys circled around two girls kissing, according to other girls who were there.

Maybe the teenage exhibitionists were just yanking guys' chains, or hoping to prove how sexy they are, or copying Britney and Madonna. But it's also possible they were enjoying themselves. There's no way for an outsider to know, for in the protean world of young female sexuality, where all forms of expression are modeled, nothing is certain.

Social scientists say that 5 percent to 7 percent of young people are gay or lesbian, and that teenagers are starting at younger ages to have same-sex sexual experiences: 13 for boys, 15 for girls.

But those figures don't begin to tell the full story about today's girls because girls, more often than boys, experiment with their sexuality and resist being placed in any particular group.

Chanda Harris, a junior at High Road Upper School in Beltsville, is one of these girls. She's standing outside Union Station on a cold Friday night, waiting for her girlfriend and holding three giant helium balloons in celebration of her friend's birthday.

The girls around her from various high schools -- Bladensburg in Maryland, Anacostia, Ballou, Cardozo and Coolidge in the District -- converge to hear what she has to say.

She started going out with girls when she was 14, following a breakup with her boyfriend.

"At first I thought going out with a girl was nasty," she says. "Then I went to a club and did a big flip-flop. I've been off and on with girls and guys since then."

Another girl, a junior at Anacostia High, says her first love was a guy now in the Marines and stationed in North Carolina. She dated Kenny for two years and his picture adorns her bedroom wall.

But now she's dating a female high school basketball player. "Whoever likes me, I like them," she says matter-of-factly.

A world away, on the campus of Brown University, Chloe Root, a sophomore with a penchant for bright-colored, funky skirts from secondhand stores, also prefers to keep her options open.

She had her first crush on a girl at age 12 but dated guys, including one with whom she thought she was in love, until her senior year in high school in Ann Arbor, Mich. Then she fell in love with a girl a year behind her in school and has been going out with her ever since.

"If something happened to my relationship with Julie, I could see myself with a boy again," Root says. "There are some days I notice I'm thinking girls are pretty, and other days I'm thinking there are a lot of good-looking guys at this school."

So are these girls bisexual? Perhaps. But they prefer descriptions like "gayish," questioning, even "queer" -- an umbrella description so broad, according to Root, that it encompasses straights as well as gays.

Try this on, Mr. and Mrs. America: These girls say they don't know what they are and don't need to know. Adolescence and young adulthood is a time for exploration and they should feel free to love a same-sex partner without assuming that is how they'll spend the rest of their lives.

"I like women only right now," says Cary Trainor, also a Brown sophomore and a self-defined lesbian since high school. "But who knows where I'll be in 25 years?"

Even gay rights veterans such as David Shapiro struggle to explain such equivocation.

Shapiro is head of the Edmund Burke School, a private, college-preparatory program in Northwest Washington. In 2002, Burke held a "diversity day" assembly in which students and teachers stood together in a circle. An adult leader took the group through various exercises, and in one of those, participants were asked to move inside the circle if they defined themselves as gay or lesbian.

One female teacher stepped forward, but no students did.

Then the leader called for those who thought of themselves as bisexual -- the broadest label offered. Out of the approximately 60 pupils in the group, 15 obliged: 11 girls and four boys.

Shapiro says he was "astounded" at the number of kids who stepped into the bisexual group. As he thought about it, he concluded that "kids today know the difference between behavior and orientation. They say, 'I may be behaving in this certain way, but I'll make up my own mind about who I am in my own time.' "

He searches for a comparison. "It's like saying, 'Mom, Dad, I'm going to take some courses in science but I'm not sure I want to be a doctor."

A Changing Model

Outside of conservative religious circles, the common understanding for years has been that homosexuality is largely genetic, based on physical attraction, and unchanging. Though an easy model to understand, if not accept, it has a major flaw: It is derived almost exclusively from male subjects.

Recent studies of relationships among women suggest that female homosexuality may be grounded more in social interaction, may present itself as an emotional attraction in addition to or in place of a physical one, and may change over time. Young women also appear to be more open to homosexual relationships than young men are. In one recent national study, more than twice as many girls as boys reported being attracted to the same sex at least once.

Girls may be reacting, in part, to relationships gone sour with guys.

Root has been surprised by the number of gay women she knows who say this. "They say that when you're with a guy, there is often a feeling that you're always going to be in a narrow feminine role," she says. "They say that guys treat them as less capable, overly emotional, or too hungry to be attached."

The Union Station girls are more blunt about it.

"Girls understand how girls think," Chanda Harris says. "You can tell a girl, 'I think I'm falling in love with you' and she'll listen. A boy will slough that off, or run away. Besides, the young boys around me are into making money, selling weed and stuff. That's not what I'm about."

A Bladensburg High senior, Kateria Rhodes, who says she has dated girls for five years, overhears Harris. "It's not the sex," she says. "Girls are there for you emotionally. Sure, they cheat sometimes, but I've found [dating girls] is better for me mentally. Actually it's better on every level."

She says she has friends who used to date girls and now date guys, and that her mother keeps telling her she'll change, too.

Harris doesn't feel that parental pressure: "My mother prefers me to be with girls than guys. She says I'm happier."

Lisa Diamond, assistant professor of psychology at the University of Utah, is one of a handful of researchers altering the way some people think about girls such as Harris and Root.

"Starting in graduate school, every study I found sampled males only," she recalls. In 1994, Diamond launched a longitudinal study of women ages 16 to 23 who said they were attracted to other women.

In the eight years she has been following these women, almost two-thirds of them have changed labels. "They've gone from unlabeled to bisexual, lesbian to bisexual, lesbian to 'heterosexual and getting married but may be attracted to women in the future,' " she says. Another word she heard was "heteroflexible."

"The reason one person ended up gay might be very different from another person," she continues. "One might know at 4, another at 30."

Diamond's research, reported in the Journal of Personality and Social Psychology, among other publications, confirms the experience of Diane Elze, who has counseled gay and lesbian youth for two decades.

"Women who come out as lesbians but lived most of their lives as heterosexuals -- does that mean they were always lesbian? I don't think so," says Elze, assistant professor of social work at Washington University in St. Louis. "Probably we're going to find out there are multiple pathways to homosexuality and that could vary by gender."

Testing the Waters

What Diamond calls "passionate friendships" among adolescent girls, nonsexual but highly affectionate, are a staple of life in late elementary, middle and high schools. Hugs, kisses and back rubs are the coin of the realm.

But as it becomes more acceptable to be gay or gayish, will heterosexual girls in such friendships wonder whether they're gay, feel pressure to act gay or even shy away from same-sex relationships for fear of being seen as gay?

Ritch Savin-Williams, a Cornell University professor who has written extensively about gay youth, doesn't think so. "The natural affection that most young girls see around them probably protects them from assuming that their desires to touch, hold and kiss mean 'being gay,' " he says.

He doesn't rule out the possibility of some confusion.

"Boys with these feelings say these attractions are homosexual but 'I'm not a homosexual.' Girls are less likely to say that, less able to separate their personal identities and sexual selves.

"They may say, 'I'm not totally heterosexual,' and unlike guys, tell someone almost immediately. It's 'Ring, ring, ring -- hey Sally, I must be bisexual.' "

Bladensburg High's Rhodes says that among the group at Union Station, peer acceptance does play a role. "Most of these girls aren't gay," she sniffs. "They're just doing it because their friends are doing it."

Girls aren't as forthright in swank, upper Northwest Washington, where being gay -- or gayish -- is still a scary proposition.

At Edmund Burke, which has the reputation of being one of the Washington area's more liberal schools, no student is officially "out," not even those who joined the bisexual circle on Diversity Day. After that workshop, a couple of girls approached Gianna D'Emilio, a junior and a member of the Gay-Straight Alliance, and talked to her about being bisexual. "They felt more comfortable once they had been in the circle," D'Emilio says.

A group of junior and senior girls at another private school in Northwest Washington, all of whom say they're straight, say that they'd rather have a gay guy as a friend than a lesbian. How about a bisexual girlfriend?

"That's too confusing," says one. The girls say they'd be mortified if their names, or the name of their school, were used.

The Either/Or Conundrum

How easy it would be to chalk gayishness up to the influence of TV and the movies (although most of Hollywood's gay characters are white males).

Comedian Ellen DeGeneres came out when girls who are now seniors in high school were in third grade. Girls have grown up with shows like NBC's "Will & Grace" and recently saw Karen, the show's bisexual socialite secretary, plant a 14-second kiss on the straight Grace.

"Kissing Jessica Stein," a 2001 romantic comedy about two young women falling in love, became a cult movie. One evening last month, three shows with lesbian themes aired on UPN.

More and more schools march in this parade as well, shepherding students into gymnasiums for assemblies on tolerance, posting rainbow stickers on classroom doors and allowing teachers to come out to their students.

Many young people, in particular young women, are making their own push for more sexual latitude and more understanding.

The number of student-organized, gay-straight clubs, formed to promote understanding of sexual orientation issues, jumped from 1,200 in 2002 to 1,970 in 2003, according to reports filed with the Gay, Lesbian and Straight Education Network, a national organization that works with schools on behalf of gay youth. In poll after poll, proportionately more young people than old people (and more girls than guys) say they accept homosexuality as a legitimate lifestyle, whenever it occurs.

That understanding often doesn't emerge until the late teens or early 20s, however. Michelle Lettiero, 23, who now works at the Department of Housing and Urban Development, remembers a girl at her Catholic high school near New Haven, Conn., who ran around with about a half-dozen other girls. The little clique drove the Sisters of the Sacred Heart crazy by dying their hair, piercing their noses, wearing knee-length boxer shorts under their schoolgirl skirts and claiming to be lesbians.

The girl went to Providence College with Lettiero. "As soon as she got there, she started having boyfriends. She dated guys all four years," Lettiero says.

Lettiero says the group's antics seemed weird to her and her friends at the time. "We were so boy-crazy. But I would hope we're more accepting now."

Romantic changeability between females is hardly a new thing in this country. Nineteenth-century women workers who lived together in the settlement houses of New York City wrote as passionately about their friendships with other women as they did about the poor whose lives they changed -- before they moved out and got married to men. First lady Eleanor Roosevelt, a powerful woman in the 20th century, enjoyed a close, 30-year relationship with Associated Press reporter Lorena Hickok.

But that was then and this is now, a politically charged, risk-averse time when Americans crave definition in order to contain what they perceive to be chaos. A loose definition of female-female love makes people especially uncomfortable.

It upsets parents who like to fit their children into easily recognizable boxes ("Do you like men or women? Pick one"). Older gay rights activists get nervous about the political consequences, because if young women adopt a homosexual lifestyle assuming it's temporary, couldn't they also choose to abandon it?

"As gays, we have predicated our acceptance by the culture on something we can't change," psychology professor Diamond says. "We say, 'Oh look at us! We can't help it!' That's what the straights want to hear."

Older lesbians who came out in the 1970s can be especially hostile to the idea of flexible sexuality, she notes, accusing the younger women of being "either repressed lesbians or curious heterosexuals who are wasting our time."

It is the older lesbians who are wasting their time, according to Savin-Williams. "Identity labels are over," he says. "This is a cutting-edge issue for all of us."

When it comes to dating, Brown student Chloe Root, above, says she prefers to keep her options open. Chanda Harris, below right, a junior at High Road Upper School, has a girlfriend and says, "Girls understand how girls think." Brown sophomore Cary Trainor, below left, says, "I like women only right now. But who knows where I'll be in 25 years?"