Module Description: Co-occurring psychiatric conditions are frequently seen in patients with substance use disorders. Clinicians should be alert to the signs and symptoms of common psychiatric disorders and should understand how to distinguish independent psychiatric disorders from substance-induced disorders. Depressive disorders and anxiety disorders, including post-traumatic stress disorder, are the most common co-occurring conditions, though ADHD is often encountered across the range of substance use disorders. Substance use disorder patients with co-occurring psychiatric disorders will respond to most standard psychological and pharmacological treatments for these psychiatric conditions, though clinicians should avoid the use of scheduled medications and must always focus on sobriety as a primary treatment goal. Treatment that integrates addiction and psychiatric care is the most effective.