This talk will review the behavioral pharmacology and treatment of substance use disorders with psilocybin and other classic psychedelics (5HT2A agonists). Early research from the 1950s to 1970s investigated classic psychedelics, primarily LSD, in the treatment of alcoholism and cancer-related distress. Over the last 20 years research has once again investigated psychedelics in the treatment of psychiatric disorders including substance use disorders, cancer-related distress, and depression. This talk will provide a current description of this work as well as a vision for the future.