Additional Study Information: The Center for OCD and Related Disorders is currently conducting a study in treating Obsessive-compulsive Disorder (OCD), which is a severe illness characterized by distressing intrusive thoughts, images, or impulses about a variety of themes (e.g., fears of contamination or harm) and repetitive behaviors such as excessive washing or checking. The study is for adults (18 and above) with OCD. The goal of this study is to advance our understanding of who benefits from adding a type of Cognitive Behavioral Therapy called EX/RP to medication, and then to find out whether those who benefit can discontinue their medication. All evaluations and treatment are confidential and provided at no cost to the patient by psychiatrists and psychologists who are experts at treating OCD and related disorders. Potential participants can call 646-774-8062 for more information and to schedule a confidential telephone screening to determine eligibility. For more information about our program, you can also visit our website: http://columbiapsychiatry.org/ocd.