AbstractIn dealing with a child with a structural defect, an overall diagnosis must be formulated. Such a diagnosis makes it possible to provide genetic counseling for the parents and an accurate prediction relative to such a child's future development. Because there are a great many abnormalities involving the head and neck, it is hoped that the approach set forth in this article will allow for a systematic narrowing of the diagnostic possibilities. Nomenclature is established. Prenatal‐onset defects are described, including both single primary defects (malformations and deformations) and multiple malformation syndromes (chromosomal abnormalities, genetic disorders, defects resulting from teratogenic factors, and disorders of unknown etiology). Genetic and environmental factors of postnatal developmental problems are also discusse