This chapter discusses the terminology and definition of nonsuicidal self-injury (NSSI). NSSI, therefore, is understood as voluntary and intentional self-destructive behaviors that are carried out for purposes other than ending one’s life. These include a wide variety of behaviors. While sexual abuse often plays a large role, emotional wounds may be particularly influential in the development of NSSI behaviors for college students. Some of the most common NSSI behaviors are pinching, scratching, cutting, ripping, and carving skin, but others include banging or punching an object or oneself until the point of bleeding, interfering with the healing of wounds, and pulling out hair. The chapter explores the manifestation and purpose of the behaviors as well as assessment and treatment. It describes an awareness of personal biases and combating socially derived stereotypes and myths about NSSI are essential processes in the understanding, assessment, and treatment of self-injury.