The proposed study is designed to determine the relationship between biopsychosocial variables and health behaviors among homeless street youth. Specifically, depressive symptoms and substance use will be examined as potential predictors of risk behaviors for HIV and Hepatitis B and C. Salivary cortisol, a biochemical correlate of depression will be analyzed to determine if a relationship exists with depressive symptoms among homeless youth. Clarifying the relationships among these multiple variables will lead to a better understanding of potential treatment options in a population of adolescents that are not served well by traditional treatment methods. Qualitative information, gathered during interviews with homeless youth, will enhance our understanding of how homeless youth perceive their risks. Further, youth will be asked to indicate any services that they have received, or could suggest, that would help them to reduce their perceived risks of HIV and Hepatitis. Findings from this research will aid future research endeavors by this author as well as others interested in creative treatment methods for this traditionally difficult to treat population.