The aim of this study was to determine whether the nature of the drug-crime relationship differs as a function of participant age (adolescent vs. adult). It was hypothesized that the Drug x Crime interaction would predict subsequent drug use and serious offending in 924 early- to mid-adolescents but not in 722 adults. All participants came from the Offending, Crime, and Justice Survey conducted in England and Wales between 2003 and 2006. The hypothesis was supported by the results of two separate two-equation multivariate linear regression analyses. These findings indicate that the relationship between drug use and criminal offending varies as a function of participant age, such that the relationship is interactive during its formative years but becomes cumulative or additive during early adulthood. The research, theoretical, and practical implications of these results are discussed.