Individuals with Prader-Willi syndrome (PWS) are at risk for psychopathology due to their maladaptive behavior profile. This study investigated the self-concept of these individuals to better understand the origin and manifestation of their psychopathology. In this cross-sectional, retrospective study, 128 individuals with PWS were administered semi-projective and behavioral measures, including the Brief Incomplete Sentences and Body Image Tasks, to gain an introspective analysis of their self-concept and explore any trends based on genetic subtype, age, gender, and/or BMI. Results showed a positive correlation between age and negative statements about the physical self, and positive statements about the non-physical self. In conclusion demographic features of individuals with PWS may predict aspects of their self-concept, which could have implications for prevention and treatment of psychopathology.