DESCRIPTION: (provided by the applicant) Substance use disorders in adolescents are a serious public health problem. They can be chronic, cause significant impairment in school and social functioning and show marked continuity with adult substance use disorders. Prior research demonstrates that drug use is especially prominent among gay, lesbian and bisexual (GLB) youth. It may be related to the increased rates of suicide attempts seen in this population. The overall goal of this study is to compare levels of alcohol and illicit substance use, in GLB youth, to those in heterosexual peers. It will also assess substance use as a potential mechanism to explain the relationship between GLB status and suicide. We propose a secondary analysis of two different samples that will include younger as well as older GLB youth. One sample is the first wave of a longitudinal epidemiological study of Puerto Rican youth, age 11- 13 years. That study compares levels of antisocial behavior in Puerto Rican youth living in one borough of New York City (N=375) to those for youth living in metropolitan San Juan, Puerto Rico (N=375). Each youth and a parent are assessed for psychiatric symptoms, drug use, impairment and risk and protective factors. Each youth also completes a sexual development interview. The other sample, (N=1,500, compares rates of suicidality in youth exposed to a recent suicide at their school to rates for youth from matched control schools. This two-stage study screens youth for psychiatric disorders, drug use, and suicidality in addition to psychosocial risk factors and sexual development. Specific aims of the proposed study are: (1) To describe and compare rates of alcohol, marijuana and other illicit drug use in different sexual orientation groups, (2) To extend the findings regarding drug use from older to younger GLB youth less than 14 years of age, (3) To examine rates of attempts, psychiatric disorders and comorbidity related to sexual orientation, (4) To examine whether concurrent psychiatric illness is a mediator in the relationship between GLB status and drug use, and (5) To examine whether drug use is a mediator in the association between GLB status and attempts. Although the proposed study uses only cross-sectional data, it offers a unique opportunity to examine sexual orientation in large samples that include significant proportions of younger and ethnically diverse youth. The findings will contribute to the description of psychiatric problems associated with a GLB orientation and generate further hypotheses to explore what mechanisms link a GLB sexual orientation with drug use and suicidality.