This authoritative, highly readable book reviews current cognitive-behavioral models of OCD and delineates an innovative approach to assessment and treatment. From leading scientist-practitioner David A. Clark, the book first elaborates on and refines existing theories of obsessions and compulsions, with a focus on the maladaptive appraisals and beliefs underlying different types of symptomatology. Building on this expanded account of obsessional phenomena--and drawing on the latest CBT theory and research--the second half of the book presents a detailed treatment manual. Specific strategies are set forth for identifying client needs, developing a cognitive-behavioral case formulation, implementing a range of carefully planned interventions, and troubleshooting potential difficulties. Illustrated with extensive clinical material, the volume is practical and user-friendly. Invaluable appendices feature over a dozen reproducible rating scales, homework tasks, and client