Non-suicidal self-injury (NSSI) has become an increasingly worrying phenomenon among adolescents and young adults. This study sought to address the paucity of data about the prevalence, nature, and functions of NSSI in the South African context. The Inventory of Statements about Self-harm and the Beck Depression Inventory-II were administered to 623 high school and university students recruited for the study. The results indicate an NSSI prevalence rate of 56.2% of the sample, with "interfering with wounds," "pulling hair," "banging heads" and "cutting" being the most common NSSI behaviour. The behaviour appeared to be associated more with intrapersonal functions like affect regulation and self-punishment than with interpersonal functions like communicating distress and maintaining boundaries. The implications of the findings for interventions and future research are discussed.