On a Saturday night in Washington, D.C., 23-year-old Evi Lalangas and her 21-year-old sister, Tina, are ready to hit the town. Tonight's location? Adam's Morgan -- a hip, young D.C. neighborhood known for its bustling night life.
On this particular night, Evi and Tina grab their stilettos and their friends and head out the door in hopes of finding Mr. Right -- that is, Mr. Right Now. These ladies aren't looking for boyfriends, but they're open to the idea of hooking up.
"When you're hooking up," said Evi, explaining her feelings, "it's 'I want to feel good right now, and this is how I'm going to feel good. I'm going to kiss. I'm going to do this and that because I want it right now and don't care who you are. We want some sort of self-satisfaction."
According to Evi and Tina, "hooking up" is broadly defined. They say it can range from kissing to making out to having sex. It's often with a stranger and, if there were any thoughts of this tryst leading to a relationship, think again.
'No Emotional Element'
"[Hooking up] means there's no emotional element," said Evi. "We hooked up, I'm physically satisfied, and I went on my way."
So, just how prevalent is this culture of hooking up? "I think it's rampant," said Tina. "Everyone does it," said Evi. "In our age group? I think everyone. I think we would honestly consider someone weird if they didn't hook up."
Pulitzer Prize-winning Washington Post reporter Laura Sessions Stepp has written a book about this phenomenon titled "Unhooked: How Young Women Pursue Love, Delay Love, and Lose at Both." The book explores what Stepp said is an alarming trend among young women.
"The final piece of it among many … is their ability to be in a relationship once they want to be in a relationship," Stepp said. "How do you learn those things like respecting each other, having trust, communicating, solving problems?"
Getting the Upper Hand
In researching the book, Stepp followed a handful of college and high school girls during a school year. Tina appears in the book under the the alias "Nicole," and is quoted describing one hookup: "The sex wasn't great," Nicole admitted later, but that's not why she had spent the night either time. "I wanted to prove I still had the upper hand. I knew he could get a lot of girls, and I was playing his own game …"
"That's correct," said Tina, when asked about that passage. "Yeah. Beating him to it. Because if you beat him to it, you're the one who kicked him out, you're the one who's emotionally detached, you don't give him time to burn you."
Tina's story illustrates the source of Stepp's worries. "Young women were telling me about hookups," she said. "They had become attached, they felt hurt, they felt used, they weren't feeling any passion, any joy in the sex they were having."
But, according to Stepp, Tina wasn't emotionally detached. She said, like almost every girl who hooks up, she was in denial and ended up getting hurt.
"That is when I thought," said Stepp, "there is something wrong here. There is something amiss here. They are not getting all that they could out of their relationships."
Girls Gone Wild?
Stepp worries these experiences will lead to troubled relationships later in life. And she calls on girls to change their behavior.
"Girls need to preserve their power, not give it away," said Stepp. "Girls are doing themselves no favors by giving it away."
Some professionals, however, disagree with Stepp's viewpoint. Deborah Tolman is a Harvard-trained psychologist and a professor at San Francisco State University. She said Stepp's views are based on bad assumptions.
"I think the whole book is premised on the idea that there is something wrong with these girls," said Tolman. "And whenever we see girls acting sexually in an overt way, in a proactive way, we get panicky. We are very anxious about women's sexuality, still, in this society."
Tolman said researchers have not studied the sexual habits of young people long enough to know how new hooking up is. She also said that research showed that the number of young women having intercourse has actually fallen in the last decade and that young women feel more empowered to say no to boys.
Fueling This Trend
Stepp, however, still worried about the long-term consequences of hooking up for girls. "If it is making you happy, and you are feeling good the next day, there is nothing wrong with it," said Stepp. "The problem is if it becomes a pattern. If it becomes the only way you know how to relate. Then it's a problem."
According to Stepp, a number of factors fuel the trend, including the sex-drenched media that glamorizes Britney Spears' partying, Paris Hilton's conquests and the alcohol-filled nights seen on shows like "Girls Gone Wild" and "Laguna Beach."
But she also pointed the finger at parental pressure to succeed and the empowerment message of feminism that leaves girls cold to the idea of a relationship.
"Women today worry that long-term relationships are going to mess up their life plans," said Stepp. "They are ambitious. Both Tina and Evi have career goals. Men get in the way of that."
Tolman said that theory doesn't hold water. "I don't think we can explain a series of disconnected relationships," she said, "if, in fact, that is what we are seeing … by the fact that women are educated and getting careers. Women have been doing that for a long time now.
"Hooking up could be a useful developmental process. It could be painful or it could be exhilarating," Tolman continued. "I don't think there is a new problem facing young adults or older teenagers. I think it's the same old problem. And I don't think it's a problem."
It Takes Two
Tolman also took issue with Stepp's focus on girls, since it takes two to hook up. "If we keep thinking it's all on girls' shoulders, we're never going to get it right," she said.
Stepp insists otherwise. "Women, rightly or wrongly, have always been the sexual gatekeepers," she said, "partly, I think, because they have so much to lose. When they started to say yes instead of no, when they started seeing this as a sign of power, one guy said to me, 'assertive girls just let guys be bigger jerks.'"
Despite all of the controversy involved in hooking up, Tina and many of her friends still believe in true love. "Yes," said Tina. "I think I'm a hopeless romantic."
And as for the Saturday night out in D.C., the girls prowled but came up empty-handed. "It didn't exactly happen tonight, but it doesn't happen every night," said Tina. Evi added that hooking up is not always the top priority when going out. "Our joke is: Hooking up with a guy or late-night food? I pick late-night food!"
ABC News' Eric Johnson contributed to this report.