In this groundbreaking book, Elinor Ostrom takes on one of the most difficult and controversial issues in positive political economy: how to organize the use of shared resources in a way that avoids both excessive consumption and administrative costs. If resources are used by many people, that is, there are no clearly defined individual property rights over them, economists often consider them suitable for exploitation only when the problem of excessive consumption is solved either through privatization or external coercion. Ostrom strongly argues that there are other solutions, and it is possible to create stable institutions of self-government if the problems of security, trust and control are solved.