The relative advantages of private property and common property for the efficiency, equity, and sustainability of natural resource use patterns have long been debated in the legal and economics literatures. The debate has been clouded by a troika of confusions that relate to the difference between (1) common-property and open-access regimes, (2) common-pool resources and common-property regimes, and (3) a resource system and the flow of resource units. A property right is an enforceable authority to undertake particular actions in specific domains. The rights of access, withdrawal, management, exclusion, and alienation can be separately assigned to different individuals as well as being viewed as a cumulative scale moving from the minimal right of access through possessing full ownership rights. Some attributes of common-pool resources are conducive to the use of communal proprietorship or ownership and others are conducive to individual rights to withdrawal, management, exclusion and alienation. There are, however, no panaceas! No institutions generate better outcomes for the resource and for the users under all conditions. Many of the lessons learned from the operation of communal property regimes related to natural resource systems are theoretically relevant to understanding of a wide diversity of property regimes that are extensively used in modern societies.