Nonsuicidal self-injury (NSSI) is the deliberate damaging of one's own body tissue in the absence of any intent to die. Although reports of this behavior span centuries, reported instances of NSSI have increased dramatically over the last 20 years. Until now, there has been no authoritative book on the topic that evaluates why this behavior occurs and what evidence-based assessment and treatments are available. Editor Matthew K. Nock has compiled the first comprehensive overview of NSSI written by leading theorists, researchers, and clinicians in the field.Drawing upon the historical, biological, cognitive, behavioral, and interpersonal literature, the contributors help to provide answers to some key questions: How prevalent is NSSI? What is its history? Does it occur more frequently among youth? Among females? What influences its occurrence? And, most importantly, how can mental health professionals help those who self-injure? The book's contributors have created a monumental and accessible study of NSSI. Understanding Nonsuicidal Self-Injury is a must-have for both researchers and clinicians, including psychologists, psychiatrists, social workers, nurses, and all who wish to help those who struggle with this disturbing behavior.The book is suitable for researching psychologist, graduate psychology students, counseling psychologists, school psychologists, clinical psychologists; and other clinical mental health professionals, such as clinical social workers and psychiatrists, educators, parents.