Nonsuicidal self-injurious behavior (SIB) occurs in both culturally appropriate and culturally inappropriate forms. It is one of the diagnostic criteria for borderline personality disorder, but it occurs in several psychiatric and neurological populations. The personal intent of SIB in psychiatric populations is incompletely understood. A self-report scale (Self-Injury Motivation Scale; SIMS) to assess motivation for self-injury was developed. Relationships among motivation for SIB, characteristics of SIB, and psychopathology were explored. A semistructured interview and the SIMS, Dissociative Experiences Scale, Beck Depression Inventory, Davidson Trauma Scale, and Millon Clinical Multiaxial Inventory-II were given to 99 consecutively admitted inpatients. The SIMS had good reliability and validity. A high SIMS score suggested distinct psychopathology. Several factors on the SIMS differentiated motivations for SIB. Patients with different SIMS factor profiles had different psychopathology.