The article presents a new promising approach in neuropsychology - study of individual differences in the formation of psychological functions at different stages of ontogenesis, in other words, a differential neuropsychology of children. Its subject is investigation and description of the types of differences and changes in structural, dynamic and content characteristics of mental processes in connection with variations in the morphological and functional organization of the brain and different types of deviations in this organization in children of different ages. The article also discusses problems of methodology, object and method of study in differential neuropsychology of children suggesting special terminology to describe phenomena observed in experimental studies.