Diagnostic interviews for substance use disorders tend to have high reliability among adults. We examined the inter-rater reliability of the substance use disorders section of the Structured Clinical Interview for the DSM, using 46 male and 25 female adolescent drinkers recruited from community and treatment sources. Inter-rater reliability was high for individual DSM-IV alcohol symptoms (kappa=0.84-1.0) and diagnoses (kappa=0.94), and for other substance use disorder diagnoses (kappa=0.82-1.0).