Many expens (Brooks-Gunn, Boyer, and Hein, 1988;Melton, 1988;Turner, Miller, and Moses, 1989) and a few public leaders (Koop, 1988) are fearful that the 1990s will see many adolescents become infected with the Human Immunodeficiency Virus (HIV). These infections will occur because some adoIescents engage in risky sexual and drug-related behaviors (Millstein, this volume) and because, unfortunately, many will not receive clear warnings, including specific behavioral strategies for preventing infection (Wilcox, this volume). But even among those adolescents who receive candid information about AIDS risks and how to avoid them, some will become infected because they fail to practice AIDS prevention behaviors. Of course, many adults also ignore disease-preventive messages, but there is particular concern that young people will recklessly expose themselves to AIDS risks.There is abundant evidence that adolescents take serious risks with their health, as compared with both adults and younger children. In 1985, the primary causes of mortality among fifteen-to twenty-four-year-olds were accidents (54 percent), suicides (14 percent), and homicides (11 percent) (Blum, 1987;Halperin, Bass, Mehta, and Betts, 1983; Millstein, 1989), events that either result ti-om or are closely related to behavioral choices. Millstein (this volume) reviews data on the sexual behavior of adolescents and the morbidity they experience due to sexually transmitted diseases. Young people also experience more accidents than adults (US.We thank the many friends who have commented on previous presentations of these ideas, including