This manuscript presents a single case study of a psychotically disturbed adult male (whom we call “Peter”), focusing on similarities and differences in Rorschach interpretation based on three different Rorschach approaches. Specific questions were raised as to whether the client suffered from a paranoid psychosis (paranoia) or paranoid schizophrenia. Three distinct models of psychopathology and Rorschach interpretation are initially presented. We then address Peter’s psychotic symptoms, according to the Parisian approach (specifically the Nancy French subgroup), the Lausanne Rorschach approach, and the American Rorschach approach (Comprehensive System and R-PAS). Analysis shows many convergences between the three approaches on the client’s nature of conflicts and links to reality, object relations, self-representation and anxiety, defense mechanisms, and disordered thinking, but interpretation of these variables differed somewhat despite agreement on a diagnosis within the psychotic spectrum. Concluding remarks discuss the divergences and point out the limitations of a case study method. Future research is suggested.