Abstract
The chapter relates to the diverse theoretical points addressing the sources and economic aspects defining the formation and behavior of nonprofit organizations. The basic aspects underlying these aspects are the principle of different demands for public goods, assumptions of heterogeneity, the principle of lack of symmetry in information, the theory of consumer control, as well as the interdependence of the economic sectors. The relationship of non profits with other sectors is also discussed.
Keywords: Theories, clients, formation and behavior, nonprofits.