If in some years the eighties can be typified from childpsychiatric perspective the device `back to the biological roots' will be in favor.

For many years the emotional and social determinants of behaviour were central, but in these days an orientation on the biological and cognitive aspects takes place.

The article is about this reorientation. It brings with it a renewed interest for integration of the several developmental aspects in one model. The possibilities of the cognitive-structural developmental model _ a biology funded model developed by Piaget and fellow-workers _ were worked out for the childpsychiatric practice.