Initially informed by concepts related to dissociative experience via the notion of Sullivan’s ‘not-me’ (1953), Philip Bromberg went on to craft a relational psychoanalysis built upon the foundation of a multiple self-state theory of mind that grew from his discussions with Stephen Mitchell and also from his attention to the literature and treatment of dissociative identity disorder (DID). Although he never claimed to be treating DID, the reader is invited to form their own opinion about the reach of Bromberg’s work. Additional concepts related to Bromberg’s perspectives, such as “relational traumatology” and the notion of the “participant-witness,” are briefly explored. Clinical vignettes illustrate these concepts.