Bivariate and multivariate analyses with longitudinal data over a 3-year period were used to assess temporal influences of family variables on the initiation of illicit drug use. Findings revealed large differences in family structure among the three racial groups. Black adolescents reported the lowest incidence of illicit drug use initiation and the weakest effects of family structure and environment on substance use. Cumulative effects of family risk factors were strongly associated with increased probabilities of illicit drug use initiation, but temporal and race variations in these effects were observed. Deteriorating changes in the family environment were stronger predictors of the initiation of drug use among Hispanic immigrants than among nonimmigrants, and family socioeconomic status was a predictor for immigrant Hispanics only. The relationship between family structure and drug use initiation varied in accordance with the context of temporal indicators of the family environment. The accumulation of family risk factors was a stronger predictor of illicit drug initiation than family structure. An appendix contains items and alphas for the family environment scales. 61 references, 3 tables, and 2 figures