Among 192 adolescents admitted to a psychiatric inpatient unit, levels of substance abuse were greater for those with both conduct disorder (CD) and posttraumatic stress disorder (PTSD) compared with either CD only or PTSD only. This difference was best explained by interactive rather than additive processes. Females were more likely to report elevated levels of state anger, trait anger, angry reactions, anger held in, anger out, and anger expressed compared with males. The findings suggest the need to assess and treat a history of or ongoing trauma experiences and behavioral problems in working with adolescents who have a substance abuse disorder, especially when there is a combination of trauma and conduct problems. Study participants were 192 consecutive admissions (61 males and 131 females, 11-17 year-olds) to an adolescent psychiatric inpatient unit in southern New England. This was the first inpatient hospitalization for 51 percent of the patients. A standard intake evaluation was used to collect the study data. Variables measured pertained to psychiatric diagnoses, trauma symptoms, and anger symptoms. Medical records were reviewed by a trained research assistant in order to code demographic information, suicidal ideation/behavior upon admission, homicidal ideation upon admission, history of physical abuse, and history of sexual abuse. 5 tables and 59 references