An Austrian sociologist who contributed substantially both theoretically and empirically to the scientific analysis of social structure. Initially he adopted a social psychological perspective focusing on interpersonal relations of workers in bureaucracies. His exploration of how formal structures of organizations constrain informal social relations of bureaucrats remains a classic of sociological analysis. Along with the Homans he established exchange theory in sociology. He was primarily concerned with applying small-scale exchange theory to large-scale issues.
Blau's orientation shifted from the social psychological to the social structural and from the micro to the macro.