This research is a secondary data analysis of the impact of adolescents' mental/substance-use disorders and dual diagnosis on their utilization of drug treatment and mental health services. By analyzing the same teenagers who participated in the NIMH Methods for the Epidemiology of Child and Adolescent Mental Disorders (MECA) study, logistic regression could be conducted for the data analysis. The results show that any of the following increased the likelihood of adolescents' treatment/service utilization: a dual diagnosis, mental disorders alone, a parent's treatment/service utilization, problematic biological children, adolescent's involvement with police/court system, adolescent having coverage for mental health care, the adolescent being male, and the adolescent living with a single, white parent with a relatively high educational level. Implications for policy and practice are discussed. (Contains 2 tables.)