Objective: The aims of this study are to compare DSM-IV criteria for alcohol and cannabis use disorders with its predecessor, DSM-III-R, and to examine the validity of the new criteria in an adolescent drug clinic sample. Method: During evaluation, a sample of 772 adolescents (63% boys, 77% white) were administered a structured interview of diagnostic symptoms and additional problem severity measures. Independent staff ratings of problem severity and treatment referral were collected as well. Results: Compared to its predecessor, DSM-III-R, application of the DSM-IV criteria for alcohol and cannabis users resulted in more abuse assignments and fewer dependence assignments. The shift in assignments appeared to be largely due to a lowering of the abuse threshold, rather than to a tightening of the dependence criteria. The external validity data generally supported the DSM- IV abuse and dependence distinction in adolescents, and the newer criteria were as valid as the older criteria. Conclusions: In contrast to DSM-III-R, the DSM-IV system yields more abuse cases and fewer dependence cases among adolescent alcohol and cannabis abusers. Validity evidence for the new criteria are defensible, yet the findings are seen as a starting point for discussing the need for tailoring substance use disorder criteria for adolescents.