Findings from the parent and adolescent assessments indicated a high prevalence of co-occurring psychiatric problems in the adolescents seeking marijuana treatment services. A full 74 percent of adolescents had severe levels of conduct disorder (CD), 77 percent had symptoms of Attention Deficit Hyperactivity Disorder (ADHD), 37 percent had severe levels of depression, and 28 percent suffered from severe levels of anxiety. Results also indicated that girls met the criteria for acute syndromes significantly more often than boys for all five syndromes. No differences were discovered for ethnic groups. The findings suggest that marijuana misuse outpatient treatment should be coupled with mental health services. Data were obtained from the Cannabis Youth Treatment (CYT) Study, which assessed 600 adolescents and their caregivers at intake, 3, 6, 9, 12, and 30-month follow-ups at 4 treatment locations (Illinois, Florida, Connecticut, and Pennsylvania). Assessments involved a 90-minute structured interview and urine screen with adolescents and an abbreviated assessment battery with parents that focused on their perceptions of the adolescent’s behaviors and symptoms. Interviews with adolescents included completion of the Global Appraisal of Individual Needs and assessments of psychiatric syndromes, family functioning, marijuana use severity, and criminal involvement. Data analysis focused on chi-square analyses and multivariate analysis of variance. Tables, references