Adolescents with substance use disorders (SUDs) have the highest proportion of co-occurring psychiatric disorders (CODs) compared to other age cohorts. Externalizing psychiatric disorders, such as conduct disorder, oppositional defiant disorder, and attention-deficit disorders, are most commonly associated with adolescent SUDs compared to older adults with SUD. The developmental psychopathology of SUD is reviewed. Categories of COD are reviewed, in turn, beginning with externalizing or disruptive behavior disorders. Disruptive behavior disorders are critical to the developmental psychopathology of adolescent SUD. Studies of co-occurring depressive and bipolar disorders are then considered in detail, examining the relationship between SUD and these particular CODs. Finally, the relationships between anxiety, thought, eating and personality disorders, and adolescent SUD are examined.