The extent to which adolescent drug treatment outcome studies address ethnicity was systematically examined. Reliability coefficients were calculated for both the search methodology used to obtain these outcome studies and the extent to which ethnicity was addressed along several dimensions. The resulting coefficients were highly reliable. Findings indicated that although investigators of 94% of the outcome studies considered ethnicity to some extent, only 28% of these studies incorporated ethnicity into their design, and only 6% of studies involved statistical analyses to examine differential response to treatment or moderating effects of ethnicity with a sufficient number of ethnic minority participants. Overall, results indicated that there is much work to do regarding the examination of ethnicity in controlled treatment outcome studies involving adolescent substance abusers. Indeed, modifications were rarely made to the treatment components to accommodate ethnicity-related variables. Future recommendations are presented in light of these findings.