This monograph, the first in a series planned to survey problems in clinical pediatrics, has been prepared by a clinician and investigator well known in the field of pediatrics. It is to be hoped that subsequent volumes achieve the excellent qualities of this first one. The book has three major sections, of which the first, comprising about 25% of the volume, deals with normal development and physiology of the fetal and neonatal lung. Much of this section discusses pulmonary function in newborn infants. Attention is given to various methods of determining pulmonary function and to the limitations of these methods. The second part, about one half of the entire monograph, deals with disorders of respiration in the newborn period. The common as well as uncommon problems are described, and these descriptions are often supplemented by tables, illustrations, and roentgenograms. Major emphasis is directed to hyaline membrane disease, the leading cause