This article introduces the Interpersonal Guilt Rating Scale-15 (IGRS- 15), a brief clinician-rated tool for the clinical assessment of interpersonal guilt as conceived in Control-Mastery Theory (CMT; Silberschatz, 2015; Weiss, 1993), and its psychometric proprieties. The items of the IGRS-15 were derived from the CMT clinical and empirical literature about guilt, and from the authors’ clinical experiences. Twenty-eight clinicians assessed 154 patients with the IGRS-15, the patient self-reported Interpersonal Guilt Questionnaire-67 (IGQ- 67; O’Connor, Berry, Weiss, Bush, & Sampson, 1997), and the Clinical Data Form (CDF; Westen & Shedler, 1999). A semi-exploratory factor analysis pointed to a four-factor solution in line with the kinds of guilt described in CMT: Survivor guilt, Separation/disloyalty guilt, Omnipotent responsibility guilt, and Self-hate. The test-retest reliability of the IGRS-15 was good. Moreover, the IGRS-15 showed good concurrent and discriminant validity with the IGQ-67. IGRS-15 represents a first step in the direction of supporting the clinical judg- ment about interpersonal guilt with an empirically sound and easy-to-use tool.