The diagnosis of people who have mental health disorders as well as substance use disorders is called co-occurring disorder. Earlier it was perceived that treatment for substance abuse disorder (drug/alcohol) was considered to be separate from treatment for mental illness (depression, anxiety and Obsessive Compulsive Disorder etc.) and was treated at different facilities using various therapeutic approaches. As a consequence, people suffered from several psychiatric disorders such as schizophrenia, bipolar disorders and depression never received treatment their substance abuse disorder. Now, we know that the cooccurring disorders impact one another and must be treated together. Integrated treatment in which both disorders must be treated at the same time; same place is a more effective approach. Diagnosis of cooccurring disorders is sometimes difficult due the fact that symptoms of mental illness can mask the symptoms of substance abuse or addiction and vice versa.