This book provides orientation in a research field that is hardly comprehensible today due to professional diversity and theoretical plurality. By describing and explaining organizations as social systems, it adopts one of many possible theoretical perspectives in sociology; however, it does so along a concept that has already been crucial for the development of organizational sociology and that today underpins one of the most powerful theories of organization. But that's not all: the sociological systems theory addressed here also allows for the relationship between organization-related perspectives and society-related perspectives. It is this societal reference that distinguishes the sociological engagement with organizations from organizational research in other disciplines.