The more things change, the more they stay the same. A girl may openly check out a boy's body these days, ask him to a movie, even kiss him in the school hallway between chemistry and world history. Her mom couldn't do those things when she was a teenager and still be considered a "good" girl.

But today's daughter dare not flirt too openly, abandon one guy for someone else too quickly or go a little too far sexually, even once. If she does, the old rules are likely to leap up and snag the bra strap that peeks sportily out from under her tank top. Kids may call her a slut, ho, skank, or any of a dozen other nasty words that used to be reserved for the truly trashy. And while she's nursing her wounds, her old boyfriend will have sailed on unharmed to the next girl.

So say young women from different neighborhoods in Montgomery County -- one group in high school, the other in college -- who were interviewed recently about a popular new book, "Slut! Growing Up Female With a Bad Reputation" (Seven Stories Press). These women say they anticipate soon being able to compete fairly alongside men in all of life's arenas save one: the sexual. Through bitter experience, either their own or a friend's, they know that Leora Tanenbaum, the book's author, is right when she says, "Some of the rules have changed, but the playing field is startlingly similar to that of the 1950s."

One high school senior stumbled onto that field two years ago in her sophomore year. At a weekend swim team party, she messed around with a classmate she was crazy about who had told her she "might" become his girlfriend. She knew girls who had gone a lot farther with guys and didn't think a lot about it at the time.

That Monday, the school hallways were abuzz with rumors about her. Strangers called her names and friends came up to ask her what in the world she had been thinking. Some days later, a "slam list" of girls' names appeared. Included with superlatives such as "the biggest prude" and "the most flat-chested" were the categories of "the biggest slut" and "most likely to become a prostitute." The girl's name was attached to the latter two.

There always have been "easy" girls in the peppery petri dish known as high school. In another book, "Teenagers: An American History" (Basic Books), Grace Palladino says the type used to be easy to spot: working-class family, no plans for college, likely to join the stenography pool. Nowadays, there is no one type, according to Nan Stein, senior research scientist at the Wellesley College Center for Research on Women. The openly sexual culture in which young people mature has come to mean this: The girl with a rep is as likely to be headed to Stanford as to a job flipping burgers.

"Twenty years ago, there was a distinction between good girls and bad girls," Stein says. "Now I think all girls are susceptible. You can be the straightest girl in the school, play an instrument in the band and go home, and still be called a bad girl."

In a Minnesota case, Stein says, this happened. High school boys wrote obscene graffiti in a school bathroom about a new student, Katy Lyle. Despite numerous complaints by Lyle and her parents, the graffiti stayed up for a year and a half. Other students, girls as well as boys, shunned Lyle, who eventually filed and won a complaint against the school for sexual harassment.

Tanenbaum, a 29-year-old New York journalist who herself was called a slut in junior high school, compiled her book of anecdotes and analysis from interviews with 50 girls and women. Of those 50, more than half had not engaged in intercourse. But in equal opportunity slutland, all kinds of behaviors bestow labels, and a young woman can never know for sure whether what she is doing will.

"There are all these gradations of relationships," says Peggy Giordano, a sociologist at Bowling Green State University who studies dating patterns. "Some are considered more acceptable than others, depending on the group." Sleeping with your steady boyfriend, for example, is not necessarily frowned upon. Manuela Hess, a high school senior, says it was common knowledge at her school last year that a certain senior couple "slept together every Wednesday night. It was a little odd, but people didn't really care."

Girls acquire reputations at younger ages than they used to. Kim Long, a counselor at Gov. Thomas Johnson Middle School in Frederick, cites an example: This past spring, two eighth-grade girls visited her office. They told her that a group of popular boys had pressured them to perform oral sex.

"Talk about kiss and tell, these boys really did," Long says. "The girls wanted to know how they could stop it. It broke my heart."

Robert Butterworth, a psychologist who pens the Teen magazine column "Ask a Guy," received this "Twenty years ago, there was a distinction between good girls and bad girls. Now I think all girls are susceptible." -- Nan Stein,

research scientist

letter recently. "I change boyfriends a lot," a girl wrote, "and everybody at school calls me a whore. But I haven't slept with anyone. How can I protect my reputation?" The letter was signed, "Not a Slut, 13."

Of course, the guys are not the only aggressors these days. "In the last few years, I've seen more girls tugging at boys' shorts, making comments about their bodies," says Long, the Frederick counselor. Tara Lewis, a high school senior, says girls warn other girls away from certain guys. "He's dirty. Don't mess with him," they'll say.

But boys have to be a lot more active to get tagged, and their reputation usually is more a laughing matter, says Janna Sherman, an Emory University junior. The male tags even sound benign: stud, player, mack. Boys are not as extraordinarily self-conscious as girls about their bodies, says Joan Jacobs Brumberg, author of "The Body Project: An Intimate History of American Girls" (Random House), and it's still the boys who get bragging rights. Counselor Long says she asked for explanations from the boys whom the eighth-grade girls had named. "The boys said that if they wanted to be invited to certain parties, they had to have a certain image."

As the case studies in Tanenbaum's book show, a reputation acquired in adolescence can damage a young woman's self-esteem for years, no matter how smart or talented she is. She may become a target for other forms of harassment. She may be raped; two out of three times, a rape victim is younger than 18, according to national surveys.

She may become promiscuous, figuring she might as well do what she is accused of doing. Or she may shut down her sexual side entirely, wearing baggy clothes and sticking close to home.

Tanenbaum says the possibility of a reputation makes almost all girls second-guess their behavior. They may not carry contraceptives with them, for example. "Girls start to think, I better be careful, I don't want to be called a slut," she says.

That's true into college, says Claire Moodie, a junior at Trinity College in Connecticut. She says she worried recently that a dress she had washed might be too tight. "I asked a friend, `Does this make me look slutty?' "

Moodie and several college friends, gathered at a coffee shop in Bethesda, rattle off other implications. "Let's say you go out on a date. You wonder, `If I do this and this, what will he think?' " Janna Sherman, the junior at Emory, says.

"You don't want to get a reputation," Emily Osinoff, also at Emory, adds, "but you do want to keep his interest."

Osinoff and the others say they do not necessarily reject friends who are considered "loose," a change from bygone years, but they admit that young women do their share of slut-calling.

Becky Doyle, a junior at Georgia State, admits that deep inside, she probably holds women more accountable for their behavior than men. "I know there's a double standard," she says. "I guess it's the way I've been socialized."

That's exactly what it is, says Stein at Wellesley: "The kids are just mimicking the adults."

In her research on sexual harassment and bullying, Stein has found numerous incidents of school authorities treating girls more harshly than boys when it came to sexual misbehavior. One of the most blatant examples occurred in a community in Texas after a group of football players mooned a group of cheerleaders, who mooned the boys back. The football players were suspended for three games; the cheerleaders were thrown off the squad.

"It's the old `women are from Venus, guys are from Mars` stuff," says Chantal Gordon, a high school senior from Silver Spring. "We're supposed to want stability with one guy, love and romance."

And the guy? Well, you know what he wants, the young women say.

If men are primarily hormone-driven, then women are going to have to take the initiative to make them behave, argues Wendy Shalit, author of another new book, "A Return to Modesty." But young women say that viewpoint both degrades men and keeps the burden unfairly on women. Why should they not take pride in their bodies and be able to dress the way they want? Why should they not be able to express their sexual feelings? "It's such a foreign concept," Doyle, at Georgia State, says, amused. "You mean, she wants to have sex?"

Tanenbaum says the responsibility for changing attitudes and behavior should not lie with young people. "The onus is on adults -- parents, teachers, older brothers and sisters," she says. "If you're standing in line at the grocery store and see some woman in spandex holding up the line, don't say, `That bimbo.' Don't talk about Clinton having a weakness and Monica Lewinsky being a tramp. If she is a tramp, he is a tramp, and if he has a weakness, she has a weakness."

Nan Stein tells parents to speak up when they hear their adolescents trashing girls or women in casual conversation with friends. She also says school officials must intervene quickly in any situation that borders on sexual harassment. Given a recent Supreme Court ruling, she believes that authorities are going to be more likely to do so.

Girls and young women say they would appreciate more opportunity to discuss the precarious nature of boy-girl relationships. Chantal Gordon enjoyed such a discussion in her junior year during one English class period. "It was so cool."

"These days they give you all kinds of sex education but they don't prepare you for how to deal with relationships," says one college junior whose then-ninth-grade boyfriend pressured her into having sex. "My mom gave me all kinds of books and talked to me about sex, but not about what guys want and what they'll do."

She doesn't want people to feel sorry for her. Her experience as a freshman, maddening as it was, did not sap her drive and ambition. She is enrolled in a prestigious science program at a major university, has settled on a graduate school track of eight years. The sexual revolution left her and her generation several gifts, including contraception. And the accompanying expectations, bad and good.

She has wrestled with those expectations and is coming to terms with them, mature enough to admit earlier mistakes and more cautious in her relationships. She made it through okay. But will the next generation? Almost all the young women interviewed asked that question.

"It seems girls are maturing at younger and younger ages," Elizabeth says, "and the issues aren't changing. They're not old enough to deal with all that. I worry for my children."