The research technique upon which the volume depends, and without which it would not have been undertaken, is that of the cross-cultural Survey. Initiated in 1937 as part of the integrated program of research in the social sciences conducted by the Institute of Human Relations at Yale University, the cross-cultural Survey has built up a complete file of geographical, social, and cultural information, extracted in full from the sources and classified by sub ject, on some 150 human societies, historical and contemporary as well as primitive. From these files it is possible to secure practically all the existing information on particular topics in any of the societies covered in an insignificant fraction of the time required for com parable library research.