This article investigates which growth anomalies require early orthodontic interception, that is before the age of 9 years. The diagnosis should be established at three levels: the skeletal jaw relationship including the facial profile, dental space problems determined by the apical base area, and function. Rather than to advise on mechanotherapy emphasis is placed on improvement of diagnostic skills because, contrary to therapy, making a diagnosis cannot be delegated. The analysis at the three diagnostic levels shows that only a limited number of situations demand early treatment. Among these are a negative overjet, a cross-bite, open mouth posture, and sometimes a space maintainer after extraction of deciduous molars. Special precautions are required when frontteeth become ankylosed at an early age after trauma. In case of doubt the general practitioner is advised to seek orthodontic counseling from a specialist.