[The birth of clinical psychology in the scientific work of Lightner Witmer]

The paper deals with the beginning of Clinical Psychology in the first years of XX century, when a central role was played by the theoretical and practical approach on mental retardation and behavioural disorders of L. Witmer. The author describes the cultural formation of Witmer, between Structural Psychology and Functionalism, and the special attention he devoted to the management and education of children affected by mental retardation and behavioural problems. ... Any child, the functions of whose brain are not developed up to the normal limit for his age, is suffering from retardation ... Retardation must be defined in terms of individual capacity for physical and mental development....