This case study used test data from a patient with Dissociative Identity Disorder (DID; American Psychiatric Association, 2013 ) to illustrate how two main personality states of the patient ("Ann" and "Ben") seemed to function. The Rorschach Performance Assessment System (R-PAS; Meyer, Viglione, Mihura, Erard, & Erdberg, 2011 ) and the Inventory of Interpersonal Problems-Circumplex (IIP-64; Horowitz, Alden, Wiggins, & Pincus, 2000 ), administered to Ann and Ben in separate settings, exposed two diverse R-PAS and IIP-64 profiles. Ann's R-PAS profile suggested an intellectualized style of information processing with few indications of psychological problems. Ben's profile indicated severe perceptual, cognitive, and interpersonal difficulties combined with suspicion and anxiety. Ann's IIP-64 profile suggested minor interpersonal problems, whereas Ben's indicated serious relational difficulties. The findings were discussed in relation to the theory of trauma-related structural dissociation of the personality (van der Hart, Nijenhuis, & Steele, 2006 ), which implies an enduring split in the organization of the personality with more or less separate entities with their own sense of self, perception of the world, and ways of organizing emotional, cognitive, and social functions. The DID personality structure is seen as a defense strategy and as a pathway in the personality development producing serious psychological pain and symptoms.