Seven subjects which have occupied the attention of many clinical and experimental pediatricians during the past few years are reviewed by recognized authorities in the current volume of this series. Stewart H. Clifford has written a lucid discussion of postmaturity, based primarily upon his own clinical experience and summarizing current knowledge of the pathophysiology, treatment and prognosis of postmature infants. Dr. Clifford's therapeutic recommendations should be of interest to practicing pediatricians and obstetricians. Charles A. Janeway and David Gitlin have provided a general review of the chemistry, physiology and clinically recognizable disorders of the metabolism of gamma-globulins, which includes practical guides to diagnosis and treatment.