More recently the impact of social problems has led to the intensive study of modern communities. The monumental work of Charles Booth, _Life and Labour of the People in London_, is a comprehensive description of conditions of social life in terms of the community. In the United States, interest in community study is chiefly represented by the social-survey movement which received impetus from the Pittsburgh Survey of 1907. For sociological research of greater promise than the survey are the several monographs which seek to make a social analysis of the community, as Williams, _An American Town_, or Galpin, _The Social Anatomy of an Agricultural Community_. With due recognition of these auspicious beginnings, it must be confessed that there is no volume upon human communities comparable with several works upon plant and animal communities. 3. The Group as a Unit of Investigation The study of societies is concerned primarily with types of social organization and with attitudes and cultural elements embodied in them. The survey of communities deals essentially with social situations and the problems connected with them. The study of social groups was a natural outgrowth of the study of the individual. In order to understand the person it is necessary to consider the group. Attention first turned to social institutions, then to conflict groups, and finally to crowds and crowd influences. Social institutions were naturally the first groups to be studied with some degree of detachment. The work of ethnologists stimulated an interest in social origins. Evolution, though at first a purely biological conception, provoked inquiry into the historical development of social structure. Differences in institutions in contemporary societies led to comparative study. Critics of institutions, both iconoclasts without and reformers within, forced a consideration of their more fundamental aspects. The first written accounts of conflict groups were quite naturally of the propagandist type both by their defenders and by their opponents. Histories of nationalities, for example, originated in the patriotic motive of national glorification. With the acceptance of objective standards of historical criticism the ground was prepared for the sociological study of nationalities as conflict groups. A school of European sociologists represented by Gumplowicz, Ratzenhofer, and Novicow stressed conflict as the characteristic behavior of social groups. Beginnings, as indicated in the bibliography, have been made of the study of various conflict groups as gangs, labor unions, parties, and sects.