To categorize interpretation of examinationresults, it is often not possible to use the normality concept, because of the fact that not sufficient data are available, on which the normality concept is properly applicable. This for instance is the case with assessment of neurolgical dysfuntion. For this reason, Prechtl developped the optimality concept. By applying this concept, the quantity of optimal functioning can be described. This is demonstrated for the neurological examination of children with behavioural problems and learning difficulties. These children as a group show a lower neurological optimalityscore, comparing them with children without this behavioural and school-difficulties. Applying the optimalityconcept in the fields of Psychiatry and Psychotherapy could be promising, because of the difficulties in using the normalityconcept in this fields.