Body dysmorphic disorder (BDD) is a devastating yet underrecognized illness. People with BDD are preoccupied with the belief that they look abnormal or ugly—when they actually do not. Their appearance preoccupations cause clinically significant distress or impairment in occupational, academic, social, or other areas of functioning. Psychosocial functioning and quality of life are typically markedly impaired, and rates of suicidality are very high. BDD is common, yet this disorder often goes undiagnosed and untreated. This book provides an up-to-date, comprehensive, and clinically focused overview of this intriguing, complex, and often severe disorder. The book contains nine sections: (1) patients, history, and classification; (2) phenomenology and epidemiology; (3) morbidity; (4) BDD in special populations; (5) assessment; (6) etiology and pathophysiology; (7) recommended treatments; (8) cosmetic treatment; and (9) BDD’s relationship to other disorders. Measures for assessing BDD are provided in the Appendix. Written by leading researchers and clinicians in the field, this book is for anyone who wants to better understand BDD, help patients overcome it, or conduct scientific research to advance knowledge. It is for mental health clinicians, primary care clinicians, and pediatricians, as well as surgeons, dermatologists, and others who provide cosmetic (aesthetic) treatment; cosmetic treatment is commonly received but virtually never alleviates BDD symptoms. This book is also for researchers and students who are interested in anxiety disorders, eating disorders, and obsessive-compulsive and related disorders. Although it is geared toward a professional audience, this book is also for anyone who is interested in or has been affected by BDD.