Homeless adolescents have remained an underserved population throughout the human immunodeficiency/acquired immune deficiency syndrome epidemic. This article reviews the recent literature investigating human immunodeficiency virus (HIV) risk behavior among street youth. Prevalence rates of both adolescent homelessness and HIV seropositivity are unknown. However, data from a number of samples document a high prevalence of HIV risk behavior, sexually transmitted diseases, and alcohol/drug use among homeless adolescents. A number of individual and social factors, often associated with street survival, propel adolescents toward high-risk behavior. For some adolescents, testing HIV positive is perceived as advantageous in the procurement of basic needs such as food and shelter. HIV risk-reduction interventions must take into consideration the cause of homelessness, access to and participation in shelter services, and individual factors (such as the effects of sexual orientation and ethnicity) that frequently have not been systematically included in previous research. HIV risk for many homeless adolescents stems directly from their state of homelessness. National policies and funding are needed to address the health needs of these youth.