This revised application for competing continuation is to expand upon the analyses of the National Survey of Adolescent Males funded under NlCHD gran R01 HD27119, which examines general determinants of condom use among young American men. This proposed project will examine the relatIonship of drug and alcohol use to sexual risk behaviors which may lead to Human lmmunodeficiency Virus (HIV) and sexually transmitted disease (STD) transmission. The project Investigates the etiology of drug and alcohol use preceding sexual activity, the consequences on condom use, and the influenc of drug and alcohol use on the onset and level of sexual activity. This wil lead to new insights about intervention strategies for these risky sexual behaviors. We will use longitudinal data from the 1988 and 1990-91 National Surveys of Adolescent Males (NSAM-1 and NSAM2) which were designed and collected by this research team. The four specific aims of this project are to: (1) Assess the prevalence and coincidence of drug and alcohol use and sexual activity among young men, as these are related to HIV and ST transmission, based on a nationally representative longitudinal sample. (2) Analyze the longitudinal factors which predispose young men toward drug and alcohol use-preceding intercourse. This analysis involves (a) examining the determinants of substance use in general, and (b) among those who have used substances, examining the determinants of substance use prior to sexual intercourse. (3) Investigate the extent to which drug or alcohol use preceding sexual intercourse determines whether condoms are used during intercourse. The analysis will distinguish the specific disinhibiting effects of drug and alcohol use on condom use, the effect of expectancies related to substance use, and the effect of shared predispositions contributing to both substance use and condom use. (4) Investigate the influence of drug and alcohol use on (a) the age of onset of sexual activity and (b) current patters of sexual activity. such as the frequency of intercourse and number of partners in the last Year.