The interest in the mechanism of the control of the individual by the group has been focused upon the study of the crowd. Tarde and Le Bon in France, Sighele in Italy, and Ross in the United States were the pioneers in the description and interpretation of the behavior of mobs and crowds. The crowd phenomena of the Great War have stimulated the production of several books upon crowds and crowd influences which are, in the main, but superficial and popular elaborations of the interpretations of Tarde and Le Bon. Concrete material upon group behavior has rapidly accumulated, but little or no progress has been made in its sociological explanation. At present there are many signs of an increasing interest in the study of group behavior. Contemporary literature is featuring realistic descriptions. Sinclair Lewis in _Main Street_ describes concretely the routine of town life with its outward monotony and its inner zest. Newspapers and magazines are making surveys of the buying habits of their readers as a basis for advertising. The federal department of agriculture in co-operation with schools of agriculture is making intensive studies of rural communities. Social workers are conscious that a more fundamental understanding of social groups is a necessary basis for case work and community organization. Surveys of institutions and communities are now being made under many auspices and from varied points of view. All this is having a fruitful reaction upon the sociological theory. 4. The Study of the Family The family is the earliest, the most elementary, and the most permanent of social groups. It has been more completely studied, in all its various aspects, than other forms of human association. Methods of investigation of family life are typical of methods that may be employed in the description of other forms of society. For that reason more attention is given here to studies of family life than it is possible or desirable to give to other and more transient types of social groups.