The changes in family life resulting from the transition from home industry to the factory system have created new social problems. Problems of woman and child labor, unemployment, and poverty are a product of the machine industry. Attempts to relieve the distress under conditions of city life resulted in the formation of charity organization societies and other philanthropic institutions, and in attempts to control the behavior of the individuals and families assisted. The increasing body of experience gained by social agencies has gradually been incorporated in the technique of the workers. Mary Richmond in _Social Diagnosis_ has analyzed and standardized the procedure of the social case worker. Less direct but more fundamental studies of family life have been made by other investigators. Le Play, a French social economist, who lived with the families which he observed, introduced the method of the monographic study of the economic organization of family life. Ernst Engel, from his study of the expenditure of Saxon working-class families, formulated so-called "laws" of the relation between family income and family outlay. Recent studies of family incomes and budgets by Chapin, Ogburn, and others have thrown additional light upon the relationship between wages and the standard of living. Interest in the economics of the family is manifested by an increasing number of studies in dietetics, household administration and domestic science. Westermarck in his _History of Human Marriage_ attempted to write a sociology of the family. Particularly interesting is his attempt to compare the animal family with that of man. The effect of this was to emphasize instinctive and biological aspects of the family rather than its institutional character. The basis for a psychology of family life was first laid in the _Studies in the Psychology of Sex_ by Havelock Ellis. The case studies of individuals by psychoanalysts often lead into family complexes and illuminate the structure of family attitudes and wishes. The sociological study of the family as a natural and a cultural group is only now in its beginnings. An excellent theoretical study of the family as a unity of interacting members is presented in Bosanquet, _The Family_. The family as defined in the mores has been described and interpreted, as for example, by Thomas in his analysis of the organization of the large peasant family group in the first two volumes of the _Polish Peasant_. Materials upon the family in the United States have been brought together by Calhoun in his _Social History of the American Family_.