U.S. women under age 25 are far more likely to become pregnant than are comparable young women in other developed countries; however, there is no such differential among older women. Young American women appear to be no more likely than their European contemporaries to marry or to engage in intercourse at a young age, but they do seem less likely to practice contraception. Why should this be so? There are grounds to argue that young American women have more limited access to effective contraceptives than do comparable Europeans, but the problem undoubtedly has social and economic aspects as well: No other Western nation has the ethnic and socioeconomic diversity of the United States--a diversity that includes the existence of an underclass alienated from middle-class values. Limited evidence also suggests that young Americans, regardless of social class, may be more prone to risk-taking than young people in other countries. Finally, another attribute of American society that undoubtedly contributes to the problem of high pregnancy rates is our ambivalence toward sexuality: Sex saturates American life--in television programs, movies and advertisements--yet the media generally fail to communicate responsible attitudes toward sex, with birth control remaining a taboo subject. In addition, a deep-seated ambivalence toward sexuality has prevented Americans from responding to the problems of unintended pregnancy as rationally as have other Western nations.