What is hooking up?
If you don’t know, then you’re probably at least 40. As any high school or college kid could tell you, hooking up refers to the phenomenon in which two people—who may or may not know each other well, or at all—get together for the express purpose of fooling around, often after a lot of drinking. (See below.) Hooking up can involve anything from kissing and heavy petting to oral sex and intercourse, but what all hookups have in common is that the physical involvement precedes an emotional relationship—if the latter develops at all. “In the dating era, students would go on a date, which might lead to something sexual,” says Kathleen Bogle, a sociologist at Philadelphia’s La Salle University. “In the hookup era, students hook up, which might lead to dating.”

How common is it?
For many young people, hooking up has become the most common way to begin sexual relationships. Rather than getting to know each other over time, two young people meet, and a hookup is proposed and accepted. A recent Stanford University study found that about 75 percent of college students hook up by senior year, and that the average number of hookups per person is 6.9 (compared with 4.4 traditional dates); 28 percent of students have 10 hookups or more during their college years, more than a third of which involve intercourse. As for the younger set, 30 percent of teenagers surveyed for a 2006 Bowling Green State University study reported having had intercourse, and of those, 61 percent said it was with someone they did not consider a boyfriend or girlfriend. “Going out on a date is a sort of ironic, obsolete type of thing,” says Elizabeth Welsh, a 25-year-old recent college graduate in Boston. “Going out to dinner and a movie? It’s so cliché—isn’t that funny?”

Is hooking up something new?

Casual sex has probably always been around in one form or other, and anyone who remembers the “free love” era of the 1960s and ’70s may have a sense of déjà vu. But sociologists say several factors have combined to make hooking up something truly new and different. A record number of women are attending college and pursuing careers, and people are getting married later—so women in their 20s are less interested in finding a spouse and settling down. And with equality between the sexes now virtually a given, many women reject the traditional notion that while it’s fine for men to treat sex casually, a woman who does so is a slut. Technology also plays a role: Cell phone texting and social networking make it easier than ever to find people looking for the same thing you are.

Is hooking up harmful?
Many college kids scoff at that very question. They say they’re just having fun, and that as long as both people understand the terms, it’s win-win. But some health professionals have raised alarms about the spread of sexually transmitted diseases, and warn that many young adults are paying a price for learning to divorce sex from feelings and attachment. “They don’t learn to build that emotional intimacy before they get physically intimate,” says adolescent gynecologist Melissa Holmes. “They may grow up not knowing how to connect with a partner on an intimate level.” James Cox, director of the counseling center at the University of Pittsburgh, says more than a quarter of his clients come in with anxiety, depression, and other emotional problems because their relationships feel superficial and confusing. “Hooking up is like any other kind of peer pressure,” he says. “We need to encourage students to make independent, healthy choices.” That may be especially true for women.

Why would that be?
Because many experts say that sexual revolution or no, most women still do not share men’s capacity for meaningless sexual encounters. One study found that women are more likely to view hookups as an avenue to finding relationships, and that when two partners hook up repeatedly, it usually means the woman wants a relationship, while the man may not. A 2007 survey found that men are more than three times as likely as women to feel satisfied after a one-night stand, while women are twice as likely to feel regret or shame. “Girls can have feelings even from the most casual hookups, whether they want to or not,” says journalist Laura Sessions Stepp, who wrote a book about the impact on women of hooking up. “And they aren’t learning what to do with them.”

What happens after college?
There’s no hard data, but some sociologists say the hooking-up campus culture may be seeping into the broader one. Craigslist has an enormously popular classified section called “casual encounters” for those looking for no-strings-attached sex, and explicit “casual dating” websites like Fling and AdultFriendFinder get far more traffic than tamer dating sites like Match.com. Still, for many young people, the thrill of bedding lots of partners without any emotional attachment does eventually wear off. “You have contact with many, many more people, but each of those relationships takes up a little bit less of your life,” says 25-year-old May Wilkerson of New York City. “That fragmentation creates a lot of loneliness.”

The alcohol factor
Hooking up has accompanied another campus trend that has been a source of concern: heavy drinking. Alcohol-related deaths, binge drinking, and drunken driving have all been on the rise on college campuses over the past decade, a recent federal report found. While some critics say alcohol has helped fuel the hooking-up trend, it could be the other way around: People may be drinking more in order to facilitate hooking up. Drinking provides “liquid courage” to initiate a hookup, says sociologist Kathleen Bogle, while also helping to allay the fear of rejection. “Alcohol gives them permission to be out of control,” she says. “If students regret their choices later, they can tell themselves and others, ‘I was drunk.’”