Sexuality "is a vital aspect of teens' lives. ... The question is whether they are going to have healthy experiences, at any or every level of sexual activity."

Increasingly, teenage sexual encounters do not occur in the context of a romantic relationship, but in an impersonal, merely sexual "hook up." One thing "nearly everyone agrees on is that STDs and risky 'anything but intercourse' behaviors are rampant among teens." The "impersonality of twenty-first-century adolescent sex victimizes girls" and "plenty of harm" is done to boys as well. When taking part in hookups "the kids don't even look at each other. It's mechanical, dehumanizing. The fallout is that later in life they have trouble forming relationships. They're jaded." This is a "profound shift in the culture of high school dating and sex."

"Teens - and preteens - are too young to fathom the consequences, both physical and emotional, of their sexual behavior." According to Lynn Ponton, a professor of psychiatry at the University of California, San Francisco and author of The Sex Lives of Teenagers, "early initiation into sexual behaviors takes a toll on teens' mental health. The result, she says, can be 'dependency on boyfriends and girlfriends, serious depression around breakups and cheating, and a lack of goals.'" As adolescents are not mentally or emotionally prepared to handle feelings and emotions that come with sex, nor financially able to support children, "early sexual activity - whether in or out of a romantic relationship - does far more harm than good."

Between 1991 and 2001 the number of high school seniors in the United States who reported that they have had sexual intercourse dropped from 54% to 46%. However, the "dominant form of teenage sexuality has changed" in that time period. "It is not penile-vaginal intercourse anymore. It's oral sex." In 2002 the doctors who run the National Longitudinal Study of Adolescent Health reported a "dramatic trend toward the early initiation of sex." According to the American Academy of Pediatrics "early sexual intercourse among American adolescents represents a major public health problem. ... Teens rank the media second only to school sex education programs as a leading source of information about sex."

In a 2003 study, 89% of girls reported feeling pressured by boys to have sex. Before "age 15, a majority of first intercourse experiences among females are reported to be non-voluntary." Teens who are sexually active at the age of 15 or under are six times more likely to drink alcohol once a week or more, four times more likely to have smoked marijuana and three times more likely to be regular smokers of cigarettes. Other research also shows that "risk behaviors often appear in clusters; parents who detect their children engaging in one risk behavior should be alert to the possibility that there may be others. For example, many teens are either using drugs or alcohol at the time of their experience with first sexual intercourse."

Girls will often become intoxicated before engaging in sexual activities because it "numbs the experience for them, making it less embarrassing and less emotionally painful." A girl is "far more likely to feel used and abused after a typical" hook up. Girls who participate in girls-only activities are far less likely to experience a teenage pregnancy and less likely to be sexually active in general.

Of US teens aged 15-19 that are having sexual intercourse almost all (98%) use at least one form of contraception. The most popular form, at 94% usage, are condoms and the birth control pill is second at 61%. Teen pregnancies in the United States decreased 28% between 1990 and 2000 from 117 pregnancies per every 1,000 teens to 84 per 1,000. Contraceptives lower the risk of conceiving a child, and if condoms are the method chosen they help prevent the spread of sexually transmitted diseases, but they are not 100% effective.

With all the issues and problems relating to adolescent sex, according to the Medical College of Wisconsin, "Ideally, teens won’t be having sex."