This investigation examined the association between misbehavior in early life and subsequent injecting drug use (IDU) among Baltimore participants in the NIMH Epidemiologic Catchment Area study. Information about early misbehavior was collected in 1981 and about IDU in 1994-1996. Conditional logistic regression models were used to estimate the degree of association between early misbehavior and IDU, with injecting drug users (n = 38) and controls matched on census tract of residence (n = 745), selected from within the same community survey sample, and assessed in a methodologically identical manner. Early misbehavior was associated with subsequent IDU, independent of the associations with sex, age, and race. The estimated risk of IDU increased with the number of reported conduct problems. Early misbehavior also discriminated between injecting drug users and non-injecting drug users. These results, which support and extend earlier findings, have public health implications for preventing and stopping the risk-laden practice of injecting drug use.