This is the first volume of a very elaborate and exhaustive study sponsored by the National Bureau of Economic Research and compiled for the International Labor Office at Geneva. When completed this fundamental work will have brought together not only all available statistics, assembled with the aid of many governments, but also a large number of interpretative monographs based upon the statistics. Its tremendous value to those interested in international affairs need not be further emphasized. The first volume, which has just been published, is, in the main, statistical, and supplies an imposing mass of material gathered from all known sources. But special attention should be called to the general introduction, which analyzes and discusses the information contained in the tables. This first volume alone is a source book of prime importance.