<CONTINUED> ''I have my friends for my emotional needs, so I don't need that from the guy I'm having sex with,'' Melissa explained at the time, sounding very much like the ''Sex and the City'' character Samantha Jones. So why, now that the boy had ''broken up'' with her, was she feeling so depressed? ''It's really stupid, I know,'' she said, shaking her head. ''It's kind of ironic, isn't it? I try to set up a situation where I won't get hurt, and I still manage to get hurt.'' On the plus side, there's a new boy who's interested in her. ''Problem is, he's annoying,'' Melissa said. ''I liked him before we hooked up. Now I can't stand him. He's so needy, and he won't stop calling.'' Melissa said she was going to wait until after Valentine's Day to tell him she was not interested. ''I want a Valentine's Day present,'' she said. ''After that, I'm just not going to answer my phone.'' (As it turned out, they broke up before Valentine's Day.) Like other high-school girls I talked to, Melissa says she doesn't see why boys get to have ''all the fun,'' although during the few months we communicated, it was clear that Melissa's hookups rarely brought her joy. She complained often about being depressed, and her hookups, which she hoped would make her feel better, usually left her feeling worse. But a few days after a hookup, she would have forgotten that they tended to make her miserable, and would tell me excitedly about a new boy she was planning to meet. When that boy failed to show or called to say he was running an hour late, Melissa's spirits would sink -- again. But when I asked Melissa whether she thought hookups worked equally well for girls and boys, she surprised me with her answer. ''It's equal,'' she said. ''Everyone is using each other. That's fair.'' Girls Just Want to Have Fun? Ashley, an outgoing junior who is friends with Jesse, met her current boyfriend at a concert in her hometown. Her parents initially balked at the age difference (she's 17, he's 21), but she was quick to reassure them. ''People assume that if the guy's older, he's the one making all the moves and using the girl,'' Ashley told me. ''But trust me, I was definitely the aggressor. I got into his pants. He didn't get into mine.'' The question of who's in control and who is getting the short end of the stick -- whether in dating or hookups -- kept cropping up. ''Guys who are 16, 17, 18, they're just totally clueless,'' said Irene, the 17-year-old from the upper-middle-class Chicago suburb. ''They'll be like, 'I kind of want you, but now that I have you, I don't really want you anymore, so maybe I should break up with you and have you as a friend with benefits.''' Irene, like many of her high-school friends, has no problem meeting boys who are in college -- and the implication is that maybe they offer something high-school boys don't. So who's hooking up with guys in high school? Freshmen and sophomore girls. ''Some senior girls won't even look at us,'' said one high-school senior from Glenview, another suburb of Chicago, ''but underclassmen, they look at us like we're gods. Which, of course, we are, so it works out well.'' He told me that he regularly hooks up with a sophomore from another school, but he doesn't take her out with his friends. ''Until I find someone special, I'm playing the ballfield.'' While many girls insist they receive sexual attention during hookups, just as many boys say hookups are mostly about pleasing the guy. Michael Milburn, professor of psychology at the University of Massachusetts, Boston, and co-author of the book ''Sexual Intelligence,'' an examination of sexual beliefs and behaviors in America, says that the boys' take is more accurate. ''Most of the time, it's the younger girl performing fellatio on the older boy, with the boy doing very little to pleasure the girl,'' Milburn says. Some girls told me that guys think it's ''nasty'' to perform oral sex on a girl. So a lot of girls will just perform oral sex on the guy ''and not expect anything in return, because she'll know that he probably thinks it's gross,'' Irene told me. But her friend Andi pointed out that many girls are themselves insecure about receiving oral sex; they'd rather just have intercourse. There's a firm belief among many experts on teenage sex that girls, however much they protest to the contrary, are not getting as much pleasure out of hookups as they claim. I was invited to a high school in Boston, where I met with a group of seniors who were debating this very issue. I relayed a conversation I'd had with Marline Pearson, a sociologist who has developed a school curriculum for teenagers called Love U2: Getting Smarter About Relationships, Sex, Babies and Marriage. ''In some ways,'' Pearson said, ''I think girls had more power in the 1960's, when they said: 'O.K., you want to get to first base? This is what you have to do.' Today it's: 'O.K., you want to get to third base? Come over.' I'm a feminist, but I think we've put girls back in the dark ages, with very little power.'' One girl, a brown-haired senior who says she sometimes hooks up with guys she meets through friends, doesn't feel that she's in the dark ages, or that she's powerless. ''If I ask a guy to come over to my house and hook up,'' she said, ''I'm the one benefiting, because I'm the one who wants to. . . . It's not just about pleasing the guy.'' Her friend, a well-spoken senior with shaggy brown hair, faded jeans and a T-shirt with the sleeves rolled up to her shoulders, listened quietly as her friends defended a woman's right to hook up. Finally, and with some hesitation, she voiced an unpopular opinion among her friends. ''I feel like women have less power today,'' she said. ''It's not just that the guy often doesn't respect the girl or the girl's sexuality, but the girl sometimes doesn't really respect and validate herself. I have a friend who's 20, and he goes on the Internet and meets 16-year-old girls from the suburbs.'' He drives out there, she performs oral sex on him and he drives home. ''Who has the power there? I think that a lot of the times girls are really self-destructive.'' ''Well,'' the first girl said, slightly annoyed, ''I don't see why a guy can have a random hookup with a girl and no one questions his motives, but when a girl does it, there's this assumption that she's a girl, so she automatically wants more out of a hookup. When I hook up, I don't want more, and it's not self-destructive. And I enjoy it.'' Dr. Drew Pinsky, co-host of ''Loveline,'' a popular, nationally syndicated radio program that has some two million listeners and that was featured on MTV, doesn't buy it. ''It's all bravado,'' he says. ''Teens are unwittingly swept up in the social mores of the moment, and it's certainly not some alternative they're choosing to keep from getting hurt emotionally. The fact is, girls don't enjoy hookups nearly as much as boys, no matter what they say at the time. They're only doing it because that's what the boys want.'' Wendy Shalit, whose book, ''A Return to Modesty,'' embodies what has been termed ''the new chastity,'' also says she believes that girls are being manipulated, but by a society that tries to convince them that they should act like boys, turning sexual modesty into a sign of weakness or repression -- something young women are taught to be embarrassed about. ''In the age of the hookup,'' Shalit writes, ''young women confess their romantic hopes in hushed tones, as if harboring some terrible secret.'' Those who embrace an abstinence-only sex-education program try to influence teenage behavior by explaining that sexual pleasure requires mutual respect and security. Sarah LaBella works for CareFirst Prevention Services, a group that has taught in junior high and high schools since 1998. One gray, frigid February afternoon, I sat in on a class she was giving to teenage girls in an unremarkable suburban Illinois high school with a view of Dunkin' Donuts. ''Do you want to know the difference between girls and guys?'' LaBella asked. Some of the girls listened intently, others doodled or stared blankly out the window. ''Guys are like microwaves. You hit the right button, and they're ready to go. We, on the other hand, are ovens. It takes a little while for us to get heated up. You have to preheat us.'' Most of the girls smiled, and several laughed. LaBella smiled, too, because if you can make teenagers laugh (with you, not at you), you might get them to actually listen. LaBella, who typically delivers her message to coed classes, knows that some teenagers tune her out between the S.T.D. slide show and the claim that ''the best sex'' happens only within marriage. But she says that many teenagers listen intently, as if hearing some life-altering wisdom. ''We know that most teenagers are never really taught what's involved in making a healthy relationship,'' she told me after class. ''They're trying to build relationships out of hookups or casual sex, and those relationships do not tend to be fruitful ones.'' But are teenagers -- and teenage girls in particular -- always ill served by choosing hookups over relationships? Jeanette May, co-founder of the Coalition for Positive Sexuality, a grass-roots advocacy and educational organization based in Washington that argues that teenagers should be supported in making their own decisions about safe sex and their sexuality, is one of the few adults I spoke to who doesn't think so. ''Often, I think girls, if they are getting as much out of it as the guys, are better served by having sex for their pleasure, without a lot of emotional attachment,'' she says. ''Because they would feel more empowered to practice safe sex, use birth control and avoid sexual interactions that would not benefit them. When girls think they are in love or in a relationship that will lead to love, they're more easily manipulated.'' Few adults would take that line. Regardless of which end of the political spectrum they find themselves on, parents and teen-sexuality experts tend to agree on one thing: hooking up is a bad thing for teenagers. They insist that it's bad emotionally and potentially bad physically. Female adolescents ages 15 to 19 have the highest incidence of both gonorrhea and chlamydia, and according to the latest C.D.C. figures, 48 percent of new S.T.D. cases reported in 2000 occurred among 15- to 24-year-olds. Many of the teenagers I talked to told me that no one they know uses condoms during oral sex, only during intercourse. ''Both conservatives and liberals have their respective blinders on when talking about teen sexuality,'' says Milburn, co-author of ''Sexual Intelligence.'' ''I can think of nothing more important than getting in schools and talking about sexual intelligence and healthy relationships, but most conservatives don't want an open and honest discussion about teen sexuality, and they oppose any conversation that doesn't focus on abstinence until marriage. And many liberals will resist any discussion that might touch on the negative consequences of unbridled sexuality. The conversation we need to have with teens is: 'What's the role that sexuality should play in an emotionally healthy person's life? What are the different ways that people can be sexual? What are the potential dangers?' '' It's Saturday Night and . . . For all the efforts to make teenagers aware of the dangers of hookups, many of the high-school students I spoke to shrugged off the idea that hooking up is ultimately a bad thing. As they see it, if they're not going to marry for another 10 years, why not focus on other things (friendships, schoolwork, sports) in high school? And if they're not hurting anyone and not getting anyone pregnant, where is the harm in a little casual fun? The truth is, teenagers may spend less of their time hooking up than adults think they do -- for many of them, friendships have become the most important part of their social lives. Kate, Caity and Adam (the group I first met at Hooters with Jesse) often spend weekend nights hanging out together and talking about sex in ways many adults would find difficult to do themselves. I met up with them again one Saturday evening, as they lounged around a friend's living room. No one was paying much attention to the music video playing on the big-screen TV. Instead, they spent the night talking about music, soccer, their town (and why it's better than the next town over), oral sex (why some people can't do it well), masturbation (whether girls do it, and if so, whether they do it in the shower) and anything else that sprang to mind. But the big news was that Kate still hadn't kissed her boyfriend. ''We talk about it all the time, but it's like whenever we get to a point when we're going to, we don't,'' Kate said. ''I feel like I'm going to have to make the first move, and I don't do first moves!'' ''Why don't girls make first moves more often?'' asked Brian, Jesse's 16-year-old friend. ''It's really annoying.'' ''Oh, they do if they're drunk!'' said Adam (the boy who likes to lift his shirt), sitting on the couch and strumming a guitar. A lot had happened since I first met Jesse. Through a friend, Adam met a girl he actually would date, except she lived too far away. The biggest development, though, was that Caity and Adam had made out at a concert in front of all their friends. ''It was really disgusting,'' Jesse said. ''They did it right in front of everybody. And it was long.'' Both Adam and Caity dismissed it as a momentary lapse. ''It just happened,'' Caity said. ''Nothing serious,'' Adam said. The two got to only first base (kissing), which is about the only base that anyone can agree on anymore. ''I don't understand the base system at all,'' Jesse said, lying on the floor and staring at the ceiling. ''If making out is first base, what's second base?'' ''We need to establish an international base system,'' Brian said. ''Because right now, frankly, no one knows what's up with the bases. And that's a problem.'' Jesse nodded in agreement. ''First base is obviously kissing,'' Brian said. ''Obviously,'' Jesse said. ''But here's the twist,'' Brian said. ''Historically, second base was breasts. But I don't think second base is breasts anymore. I think that's just a given part of first base. I mean, how can you make out without copping a feel?'' ''True,'' Jesse said. ''And if third base is oral, what's second base?'' ''How does this work for girls?'' asked Ashley, the 17-year-old junior. ''I mean, are the bases what's been done to you, or what you've done?'' ''If it's what base you've gone to with a girl, you go by whoever had more done,'' Jesse told her. ''But we're girls,'' Ashley said. ''So we've got on bases with guys?'' ''Right, but it doesn't matter,'' Jesse said. ''It's not what base you've had done to you, it's what bases you get to.'' Kate shook her head. ''I'm totally lost.'' ''See how complicated this is?'' Brian said. ''Now if someone asks you, 'So, how far did you get with her?' you have to say, 'Well, how do your bases go?
