This chapter examines the need for effective approaches to commons problems that are global, in scale in the context of an analysis of the nature of common-pool resources and the history of successful and unsuccessful institutions for ensuring fair access and sustained availability to them. The "rational" user of a commons, Garrett Hardin argued, makes demands on a resource until the expected benefits of his or her actions equal the expected costs. Empirical studies show that no single type of property regime works efficiently, fairly, and sustainably in relation to all common-pool resources (CPRs). CPR problems continue to exist in many regulated settings. It is possible, however, to identify design principles associated with robust institutions that have successfully governed CPRs for generations. Whether norms to cope with CPR dilemmas evolve without extensive, self-conscious design depends on the relative proportion of these behavioral types in a particular setting.