In recent years, the number of scholars doing research and teaching on the nonprofit sector, the number of research and teaching centers dedicated to it, and the number of books and journals focusing on the topic of nonprofit organizations have all grown significantly. Nonetheless, this is the first book that explicitly recognizes and emphasizes the role and behavior of the nonprofit sector in the mixed economy.The book's twelve chapters present a picture of the nonprofit sector and its relationship with other sectors of the mixed economy and analyze theoretically and empirically various aspects of this relationship. The book offers new perspectives on the role of nonprofit organizations vis-à-vis for-profit firms and government organizations, a theoretical reevaluation of the relationship between government expenditures and private contributions, and a critique of the econometric studies of the "crowd-in" and "crowd-out" issues. It presents new analysis of the relationship between government expenditures and competition between nonprofit organizations and for-profit firms and new results on the Pareto efficiency of philanthropy, offering comprehensive statistical information on key variables in nonprofit organizations in comparison with for-profit firms and government organizations in several countries.