Dual Diagnosis is not itself a diagnosis, but a descriptive term for patients who have at least one psychiatric or psychological condition, and also have at least one chemical dependency condition. It is common for Dual Diagnosis patients to have several psychological conditions as well as several chemical dependency conditions. The treatment and management of Dual Diagnosis patients requires the varied medical and psychological skills.

Common examples of Dual Diagnosis patients include Bipolar Disorder with Marijuana and Stimulant Abuse, Schizophrenia with Hallucinogen Abuse, and Major Depression with Alcohol Abuse. Treatment can involve medical management, psychological management, case management, management of living situation and structuring of daily living, and coordination with recovery social models such as AA, Smart Recovery, or other similar programs.