It is accepted among those interested in orthodontia that congenital, hereditary and also acquired conditions are factors in the etiology of malocclusion and mouth breathing. The former are at present beyond our control. However, certain of the acquired conditions, ricketts, local dental lesions, malnutrition, and adenoids, can be controlled by preventive and curative measures. Adenoids, in particular, have been blamed for a very large proportion of those suffering from misshapen jaws. It is not yet known in what manner and how early in the child's development these acquired conditions produce their effects, and such data are essential to a rational effort at preventive therapy. The scope of the work as originally planned involved a study of rachitic infants, infants with large tonsils and adenoids, mouth breathers, and a comparison of these palates with the palates of normal children. It was found that no satisfactory measurements of the infantile palate had