The need for a separate clinical disorder for nonsucidial self-injury (NSSI) has been recognized for over a decade. Although the NSSI has been recognized as a behavioral symptom separate from other disorders like borderline personality disorder, only recently have attempts been made to formally specify criteria for a NSSI disorder (NSSID). This chapter reviews the attempt to include NSSID in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders, including problems with the field trial. Relegated to the section requiring further study, this chapter also critically evaluates the evidence for and against the proposed criteria for NSSID. This chapter examines possible improvements to the NSSID criteria, as well as discussing alternatives to NSSID. The chapter closes with a discussion of the importance and utility of an NSSID diagnosis.