This program has at its foundation the use of ritual prevention and prolonged actual and imaginable exposure exercises. Therapists will learn the best methods for assessing OCD and formulating a treatment program tailored to their client's particular OCD symptoms. Sample lists of exposure items are provided for fear of contamination, fear of supernatural harm, and fear of causing harm to self and others by acts of negligence. This Therapist Guide is designed to help psychotherapists in assessing and treating obsessive-compulsive disorder (OCD). It is divided into three sections. In the first section, a summary of the symptoms of OCD and methods for assessing the disorder are presented. In the second section, the relative efficacy of the available treatments and how to arrive at treatment recommendations for individuals with OCD who seek treatment are discussed. In the third section, a guide to cognitive-behavioral treatment by exposure and ritual prevention is provided.Also in this section, the components of the treatment procedures whose efficacy has been experimentally documents are described and illustrated, as well as those aspects of their practical application that inhabit experimentally uncharted territory of clinical wisdom and artistry.