This study describes the occurrence of mood disorder in a group of adolescent inpatients involved in self-cutting behavior. Although self-cutting is generally said to be associated with borderline personality disorder, a substantial number of patients who cut themselves in our study were clinically depressed. In addition, the self-cutting adolescents had a high prevalence of child abuse, past psychiatric history, and family psychiatric history. The incidents tended to spread by contagion and occur at times of change affecting the milieu. Clinical implications of these findings are discussed.