So called `Defect-theory' in the approach to the diagnostics and the treatment of mentally ill, mentally retarded children is in the recent time more and more a debatable matter. The developmental approach to this problems gets the attention of the professionals.

Through the developmental approach the child (and not his handicap) becomes the focus of the care. A developmental-dynamic model for the diagnostic and treatment goal of retarded children with mental illness is described. The theoretical base and the practical application of the model in the diagnostical is given.