There is emerging broad agreement among social, political and economic sciences that the institutions of modern society can be divided into three sectors: state, market and the awkwardly named “third sector”, but there is little agreement on the nature of the latter. This book details commons theory as a theoretical basis for understanding both the third sector and the organizations and institutions of which it is composed. In the first chapter, a number of existing perspectives on nonprofit organizations and voluntary action are examined. Chapter Two proposes the commons theory emerging from Hardin’s tragedy of the commons as a potential metaphor for both the third sector and the voluntary associations that are said to be the most distinct...