Prior research has found a positive relationship between delinquency and early onset of drug use. However, little is known about the influence of delinquency on drug initiation through mid-adulthood. This paper investigates the long-term relationship between serious adolescent delinquency and the onset of marijuana and cocaine use among an epidemiologically defined community sample of African American males and females followed from first grade through age 42. Using propensity score methods we match individuals on several etiological variables that may explain both delinquency and drug use in an attempt to examine the extent to which there may be a causal link between delinquency and drug use initiation. Through a comparison of survival curves on the unmatched and matched samples of serious delinquents and non-serious delinquents, we find that serious adolescent delinquency has at least some causal influence on drug use initiation that extends into mid-life. We discuss how these results can inform future research and delinquency and drug prevention and intervention initiatives.