are directly related to economic and social conditions in low-income neighborhoods and to the availability of guns in American society. The rise in teenage homicide and suicide also suggests increasingly high levels of hopelessness, grief, and anger among adolescents. Because of high injury and violence rates, young people in the United States are far more likely to die during adolescence than teenagers in other industrialized countries. Perhaps most important is the fact that the most salient causes of adolescent mortality and morbidity are entirely preventable.
Adolescence is characterized by exploration and experimentation, behaviors that to some extent are developmentally appropriate and socially adaptive, even if they involve a certain amount of risk-taking. Risk-taking involves, among other things, exploration, imagination, developing new and more intimate relationships with peers, testing new levels of independence, establishing a new identity, developing values, unleashing creativity, trying on different hats to see what fits. Carried to extremes, however, risky behaviors may impair mental and physical health. And health risks, such as pregnancy and substance use, may be problems not just when they happen; the consequences of these acts can reach far into the future, and their antecedents are very likely to emerge even before adolescence. But just as adolescence is a time when damaging patterns of behavior can begin to take hold, it also represents an excellent opportunity for the formation of healthful practices.
A large proportion of adolescents in the United States are engaging in sexual activity and at earlier ages than before, often without the knowledge or skills required to protect themselves from unintended pregnancies and infection with sexually transmitted diseases, including HIV. Studies show that by the 12th grade, nearly 70 percent of adolescents have had sexual intercourse, and approximately a quarter of all students have had sex with four or more partners. This puts many adolescents at high risk for unintended pregnancy, increased incidence of sexually transmitted diseases, and a host of emotional problems associated with a lack of preparation for sex.
For teenagers of different ages, at different stages of cognitive and emotional development, and living under different social, economic, and cultural circumstances, choices concerning sexual behavior reflect very different degrees of rational thinking and conscious decision making. A