Abstract The purpose of this study was to evaluate the psychometric properties of a measure, the Alexian Brothers Urge to Self-Injure Scale (ABUSI). The ABUSI was designed to assess the severity of the urge to engage in non-suicidal self-injury. Non-suicidal self-injury is the deliberate damage of body tissue that is not sanctioned by society and is devoid of an active intent to die. Participants included 386 adolescent and adult patients (90.7% female, 86.3% non-Hispanic white) admitted to a psychiatric facility for the treatment of non-suicidal self-injury. Patients were administered the ABUSI as well as measures of the frequency of self-injury, quality of life and satisfaction, functional impairment, and suicidal ideation at admission and discharge as part of routine clinical assessment. Results provide preliminary support for the reliability and validity of the ABUSI as a measure of the intensity of the urge to self-injure. Specifically, the ABUSI demonstrated adequate internal consistency, test–retest reliability, sensitivity to change, and convergent, predictive, and incremental validity. Findings suggest the ABUSI is a promising tool for both clinical assessment and research.