Nonsuicidal self-injury (NSSI) is direct, intentional harm to one’s own body performed without the intent to die. NSSI has a marked developmental onset reaching peak prevalence in adolescence. NSSI is present in the context of multiple psychological disorders and stands alone as a separate phenomenon. Research has accumulated over the past several decades regarding the course of NSSI. While great advances have been made, there remains a distinct need for basic and applied research in the area of NSSI. This chapter reviews prevalence rates, correlates and risk factors, and leading theories of NSSI. Further, it reviews assessment techniques and provides recommendations. Then, it presents the latest evidence-based treatment recommendations and provides a case example. Finally, cutting edge research and the next frontier of research in this area are outlined.
