According to Nichole Murray-Swank, an assistant professor at Loyola College in Maryland, general surveys as well as her own research indicate that 70 percent of 19-year-olds have had sexual intercourse. Just last month, a study in the American Journal of Public Health (AJPH) even called into question an earlier statistical link between virginity pledges, first popularized by Christian groups, and a delay in teen sex.

But for many, the case for virginity is far from closed.

After all, as even the AJPH study noted, surveys of intimate activity are vulnerable to the changing beliefs and behaviors of participants. Some may be reluctant to admit sexual activity, others reluctant to deny it. And in a politically charged climate that pits the teaching of abstinence against the teaching of safe sex, advocates on both sides use data to gain ideological advantage - or at least more funding.

Virgins seem to have gotten lost in the numbers. But a confident minority do still choose virginity, their decisionmaking seemingly impervious to statistical expectations or the imprimatur of popular culture.

Many of them are motivated by religious beliefs. Ms. Murray-Swank, who tracks spirituality, religion, and sexuality in adolescents and adults, has found that those who regularly worship, pray, and consider themselves religious see sexuality as part of a broad faith journey. Their views are often shaped since childhood by church and home. "Most major world religions do tend to encourage abstinence," Ms. Murray-Swank says, and the more religiously conservative the believer, the less the likelihood of sex before marriage. The correlation between abstinence and strong religious belief is "robust, persistent, and consistent over time," she says.

Paul Wiegner, like many young people, seeks to live a service-oriented life, an outlook that influences his personal relationships and his sexual activity. A student at Eastern University, a Christian liberal arts school in suburban Philadelphia, Mr. Wiegner was raised by missionary parents in Bolivia and Costa Rica, and belongs to both Baptist and Mennonite congregations. Wiegner says his pacifist, Mennonite side frames his moral decisionmaking. When asked by an 11th-grade Spanish teacher to write a personal statement, he recalls, he included the intention to save sex for marriage. "When I'm in a relationship, it's always in the back of my mind," he says.

The call to chastity is an offshoot of his attempt to model his life on Jesus, adds Wiegner, who aims to work in mediation or conflict resolution. "I've tried to center my life around serving others and serving God, and being a virgin fits into that," he says. "I don't see it as a bunch of rules to follow, but a lifestyle to lead."

If researchers tend to see sex as a laundry list of activities and a source of STDs, those favoring virginity until marriage tend to see it as part of a larger whole.

At Eastern, affiliated with the American Baptist Church, Bible-based sexual ethics puts intercourse squarely within marriage, says Joseph Modica, a professor of Bible studies. "We see Jesus affirming the marriage bonds" in the gospels. "We try to stress that abstinence is part of virtue education rather than just a matter of willpower," he says. "We try to help students understand the role of temperance, of prudence."

Recently, single-sex, student-initiated groups have emerged on campus, regularly meeting to discuss topics like modesty and Christian adult sexuality. But students are also warned against rushing into marriage. "Dating and courtship are wonderful. Marriage is a very long commitment," says Professor Modica.

Even single adults in their 30s and 40s struggle with these decisions, says Betty Jean Wolfe, president of the Urban Family Council, a Philadelphia nonprofit that partners with area churches to provide abstinence education. "We live in such a sexualized society that if you expect to have hope of being desired by the opposite sex, you'd better be 'giving it up,' " she says. For many, the pressure has led to de facto timetables for having sex, she says. "To get down and dirty about it, there's a three-date rule. Oh, for some, maybe it's after five dates, or maybe after a month. But for a vast majority, it's accepted that this is what they do."

Although statistics suggest that many believers ignore their religion's teachings rejecting sexual activity outside marriage, Ms. Wolfe says a personal embrace of faith is what brings true behavioral change. Such conversion experiences occur across denominations and creeds and correlate with abstinence, she says.

Barba, who graduated from Penn State in May with a psychology major, recalls moving from a mind-set of abstinence to one of chastity. "I was taught not to have sex until you get married," she says of her Roman Catholic upbringing, "and I thought, 'that's what I'm going to do.' " But with a longtime boyfriend, abstinence in high school was a burden. "It was always 'no, no, no.' It was a bad thing."

For her, spiritual growth began in earnest at a high school retreat and flourished when she got to Penn State. There, she became involved with campus ministry, and with Generation Life, a youth group advocating pro-life and chastity. She was struck by the association of abortion, which had long offended her, with extramarital sex, and began to embrace Pope John Paul II's "theology of the body." "It takes the emphasis off the 'no's'," and focuses on the virtue of chastity, she explains. "I came to see that my sexuality is good. In God's plan, my sexuality is a key part of me, and how can I treat it the best? How can I treat it with respect?"

Barba says her commitment has been the subject of intense curiosity from fellow students, as well as the target of jokes. But life at a large university - and the experience of seeing some fellow students fall victim to pitfalls there - affirmed her choices. "My value doesn't just come in relationships. Chastity allows you to get to know yourself - there's not the fear of being used, of having a pregnancy. It has allowed me to be free."

To Ronya Gordon, a Conservative Jew and sophomore at Brandeis University, in Waltham, Mass., the ultimate goal of sexuality is the mitzvah - or commandment - to marry and procreate and continue the Jewish tradition through her children. "I was raised with a certain set of values that were backed by Judaism - values of self-respect, of modesty," she says.

While her Orthodox friends wear shirts that cover them from wrist to collarbone, and skirts that cover waist to ankle, Ms. Gordon wears shorts and tank tops, but nothing extreme. "Once you present yourself a certain way, people get a certain idea about you and your values."

She was educated since kindergarten in Jewish schools where the standard was clear: "You are created in the image of God. Therefore treat yourself with respect, much like you'd treat another with respect." The interpretation is personal, though. Some fellow students have taken a "guarding of your body" approach, which prohibits any touching of the opposite sex - even one's fiancé, even shaking hands - until marriage. Gordon's take is different. "The message I got was 'it's your decision to make, make it a responsible one,' " she says.

For her, that begins with love, and may or may not include saving herself for marriage. "Virginity is not something I take lightly. I don't have a problem saving it for marriage.... I'm a little bit of a romantic. I'm holding out for love."