This volume addresses the need to revisit the very economic theories that in the past two decades have contributed so much to the development of a concentrated research agenda on nonprofit organizations. Long neglected as a topic of theorizing and empirical investigation by mainstream economics in particular, these initial theories of nonprofit organizations, introduced by Burton Weisbrod (see Chapter 3 by Kingma and Chapter 4 by Slivinsky) and Henry Hansmann (see Chapter 5 by Ortmann and Schlesinger and Chapter 6 by Hansmann) and others in the late 1970sand early 1980s, continue to shape theoretical and conceptual efforts. Importantly, their influence extends beyond economics and informs sociological and political science approaches to the set of organizations and institutions located between the market firm and the state agency as well (see Chapter 10 by Wolpert, Chapter 11 by Salamon, and Chapter 12 by Wolch; also Anheier & Ben-Ner, 1997; DiMaggio & Anheier, 1990). While the theoretical map of nonprofit research has expanded beyond these early attempts and now includes several other major theories such as stakeholder approaches (Chapter I by Ben-Ner and Gui, and Chapter 7 by Krashinsky), supply-side or entrepreneurial theories (Chapter 8 by Badelt and Chapter 9 by Young), institutional theories (Chapter 17 by DiMaggio), and comparative approaches (Chapter 15 by Anheier; see also Salamon & Anheier, 1998), we nonethelesssuggest that it is time to takestockand reexamine some of the very basics from which these economic theories operate. This is the main purpose ofthe book.