Students of international affairs should bear in mind that the much-discussed economic pressure that underlies all relations between states in modern times rests ultimately upon the status of populations. There has always been a great dearth of good books on population problems, and therefore this volume, written by the director of the Scripps Foundation for Research in Population Problems, is all the more welcome. Thompson surveys the most urgent population questions in the world today, in Japan, in China, in India, in Italy, etc., and considers in detail the present tendencies and the prospects of a satisfactory solution. The Pacific, Australia, South Africa and other sparsely settled areas are viewed from the standpoint of possible colonization. No one will lay down the book without being deeply impressed with the unsatisfactory nature of the existing conditions and of the tremendous importance of fearless statesmanship in dealing with this crucial problem.