Chapter 8 first provides an overview of the stipulations regarding how things held in tenancy in common (the most common co-ownership form of property around the world) should be administered and sold, as well as co-owner agreements not to partition. Then, Chapter 8 addresses whether the several types of rules lead to underuse or overuse — that is, whether tenancy in common may lead to tragedy of the commons or anticommons. The prevalent doctrine that provides one co-owner with a unilateral power to call for partition avoids a long-term tragedy but underinvestment and underuse of co-owned resources are still likely. This chapter ends with a proposed solution to ameliorate the underinvestment and underuse problems.