Mood disorders (MD), including depression & bipolar disorders, are the most common psychiatric comorbidities among patients with substance abuse (SA) disorders. Treating patients¿ co-occurring MD may reduce their substance craving & enhance their overall outcomes. A staged screening & assessment can ease the diagnostic challenge of distinguishing symptoms of affective MD from manifestations of SA intoxication & withdrawal. Treatment should maximize the use of psychotherapeutic interventions & give first consideration to medications proven effective in the context of co-occurring SA. Expanded commun. & collab. between SA & mental health providers is crucial to improving outcomes for patients with these difficult disorders. Illus