This study compared the social skills functioning and sex role affiliation of female inpatients diagnosed with borderline personality disorder who engaged in self-mutilating behavior (n = 30) with female patients with borderline personality disorder who did not engage in such behavior (n = 18). Patients with borderline personality disorder who engaged in self-mutilating behavior were found to have relatively poorer skills in communicating non-verbal emotional information to others and in receiving and interpreting such information from others. In terms of sex role orientation, patients who engaged in self-mutilating behavior were significantly more likely than non-mutilators to be typed as undifferentiated using the Bem Sex Role Inventory. These participants were less likely to identify with either masculine or feminine sex roles. Patients who did not self-mutilate were found to be significantly more likely than those who did self-mutilate to identify with the masculine sex role.