The paper proposes a reflection on the role of Italian psychology in the construction of a racist view of psychological differences. To achieve this aim, "Principi di psicologia razziale", published in 1941 by Mario Canella, who was the most authoritative interpreter of racist conception in the psychological field, has been analysed. Canella's contribution concurred to legitimate a social representation of human races and their psychological characteristics, which spread through institutional forms and penetrated into the public opinion at various levels. Canella's text has been content-analysed and submitted to correspondence analyses to explore and describe psychological characteristics ascribed to the various races. The results allowed to outline the relations among the four racial groups described (primitives, black people, Asiatics and white people) and among the eight European groups. The results have been interpreted by the Social Identity Theory.