He is the Executive Director of Western Suffolk Psychological Services in Huntington, Long Island, New York, a private clinic dedicated to the treatment of neurobiological disorders. Dr. Penzel is the author of the self-help book Obsessive-Compulsive Disorders: A Complete Guide To Getting Well And Staying Well, and also The Hair Pulling Problem: A Complete Guide to Trichotillomania. Dr. Penzel is a charter member of the Science Advisory Boards of both the Obsessive-Compulsive Foundation and the Trichotillomania Learning Center. He is also a frequent contributor to the newsletters of both organizations. Dr. Penzel conducts numerous workshops and lectures on OCD, Trichotillomania, and related disorders both nationally and internationally.