This handbook examines evidence-based treatment of obsessive-compulsive and related disorders for a broad clinical audience. Focusing on both children and adults with these conditions, it discusses various manifestations of OCD (e.g., contamination, perfectionism), related conditions (e.g., hoarding, trichotillomania, and Tourette syndrome), and cases with complicating factors. Chapters describe case specifics, offer assessment guidelines, and illustrate evidence-based psychotherapy. Case examples depict real-life complexities of presentation, notably in terms of comorbid conditions and hard-to-treat subpopulations.

Part I. Adult Obsessive-Compulsive Disorders.- Introduction.- Contamination OCD.- Sexual Obsessions.- Scrupulosity.- Aggressive Obsessions and Checking.- Symmetry.- Perfectionism.- Part II. Pediatric Obsessive-Compulsive Disorders.- Contamination OCD.- Sexual Obsessions.- Scrupulosity.- Aggressive Obsessions and Checking.- Symmetry.- Perfectionism.- Not Just Right Experiences.- Part III. Obsessive-Compulsive Spectrum Disorders.- Tourette Syndrome.- Trichotillomania.- Hoarding Disorder.- Body dysmorphic disorder.- Excoriation.- Part IV. Special Populations and Considerations.-  OCD in young children.- Tourettic OCD.- Extreme Family Accommodation.- Comorbid Autism Spectrum Disorder.- Pediatric Autoimmune Neuropsychiatric Disorder Associated with Streptococcus/Pediatric Acute-Onset Neuropsychiatric Syndrome.- Comorbid Disruptive Behavior Disorder.- Comorbid Depression.- Poor Motivation.- Poor Insight.- Obsessive-Compulsive Personality Disorder.- Treatment refractory.