Adolescents are at high risk for negative health outcomes associated with unprotected sexual intercourse including infection with human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) and unintended pregnancy. That unprotected sexual intercourse is the risk behavior common to both problems has not been fully capitalized on in prevention programs. Limited knowledge about the effects of type-of-outcome expectancy (i.e., disease vs. pregnancy) on the association between risk perceptions and precautionary or health-protective sexual behavior makes it difficult to determine what preventive approach would be most effective with adolescents. The literature suggests that pregnancy prevention is a greater concern for adolescents than disease prevention. This review focuses on the implications of these differential risk perceptions for HIV/AIDS prevention programs targeting adolescents.