The birth rate among unmarried United States teens has been sufficiently high over the last several decades that large numbers of public and private agencies have implemented a range of primary prevention strategies in hopes of reducing the number of adolescent pregnancies. Prevention strategies reported in the literature have varied in philosophy, purpose, structure, and content (Orbuch, 1989). Some interventions have focused solely on education and some on getting adolescents to abstain from coital activity, whereas others have concentrated on teaching adolescents cognitive and interpersonal skills thought to decrease the chance of youthful pregnancy. This article reviews published evaluations of these primary prevention strategies with a two-fold purpose. First, it will identify prevention efforts that have been adequately evaluated and whose results have been published in peer reviewed journals, with a primary focus on those programs that have demonstrated some level of behavioral success with sexual activity and birth control use. Behavioral outcomes are focused on here because the relationship between these variables and pregnancy is clearer than the relationship of other variables, such as attitudes or behavioral intentions. Second, the applied implications of these findings will be explored. The Need for Primary Prevention The need for pregnancy prevention efforts among U.S. youth has been consistently documented since the early 1970s. Although the age of first coitus and the frequency of coitus for adolescents in our society is comparable to other Western developed countries, the pregnancy, abortion, and birth rates among our youth far outstrip these other nations (Jones et al., 1985). The most recent figures can be extrapolated to suggest that over one million teens in the U.S. will become pregnant annually in coming years (Henshaw & Van Vort, 1989). Moreover, the most recent trend has been for single mothers to keep their children rather than relinquish them through adoption (Miller & Moore, 1990). This movement significantly contributes to increases in the number of children in poverty conditions. Many of these mothers are at serious risk for giving birth to additional children while single, thereby compounding their families' life challenges. The differences in adolescent pregnancy rates between the United States and other Western countries have often been pointed out (cf. Hayes, 1987). Such disparate figures raise serious questions about why differences exist. Jones et al. (1985) compared the U.S. to six other Western nations and concluded that differences in how the problem was defined contributed to the discrepant rates in teen pregnancies. They found that teen sexual activity, although not always seen as appropriate, is accepted as inevitable in most other countries. Although the value of abstinence and postponing coitus is often stressed, policy makers in these nations believe that programmatic emphasis needs to be centered on preventing pregnancies among adolescents because of potential costs to youth, their offspring, their families, and society. The U.S., however, has yet to clearly define the focus of the problem and attempts to do so are highly politicized. Whereas there are some who take a stance similar to that found in other Western countries, others feel that the problem rests in preventing sexual intercourse from occurring among youth. Unfortunately, the discourse surrounding problem definition is rarely dispassionate. Quite the opposite, the announcement of any intended adolescent pregnancy prevention effort within a community is likely to be met with impassioned rhetoric from concerned groups of citizens who strongly believe their approach is the correct one (cf. Kenney, 1986; Kirby, Barth, Leland, & Fetro, 1991). The ramifications of this social and cultural environment on practice will be explored later in this article. BASIC RESEARCH EVIDENCE ON THE EVIDENCE OF SEX EDUCATION One source of evidence about the relationship between sex education and pregnancy prevention comes from several national probability surveys that have been intermittently conducted since the mid-1970s. …