This study found that personal and environmental variables during adolescence predicted generalized risk for five psychosocial health problems in early adulthood: sexual risk for HIV and other sexually transmitted diseases, criminal victimization, alcohol use, and problem drug use. The relevant personal and environmental variables in adolescence that increased risk for these health problems were the use of alcohol or cigarettes by significant adults when the youth was in the 7th grade, multiple offers of these substances, deviant adolescent behaviors, doing poorly in school, adolescent smoking, being a male, and being younger than others in one's grade cohort. The findings suggest that interventions in adolescence to address and change the aforementioned factors can reduce the likelihood of identified health problems in early adulthood. This study was the RAND Adolescent/Young Adult Panel, which is a longitudinal cohort first surveyed during the seventh grade (age 13) and then followed for 10 years. The sample was recruited from 30 California and Oregon middle schools that were selected to represent a wide range of community environments. The initial sample consisted of 6,527 boys and girls. The data used in the study ultimately came from the 3,392 participants who responded to the initial 1985 survey and then to the follow-up survey in 1995 (age 23) and who completed information on sex-related risk, victimization, and alcohol and drug use in 1995. Health indicators measured at age 23 pertained to risk of sex-related diseases, alcohol problems, problem drug use, cigarette use, and criminal victimization. Variables measured at age 13 were sociodemographic characteristics, academic performance, substance use, deviance, and family and social environment. 2 tables, 1 figure, and 93 references