Market approaches to environmental conservation, by which mechanisms such as property rights, prices, and contracts are used to advance environmental goals, have gained traction globally in recent decades. But in many cases, antiquated rules limit their role in conserving public natural resources. “Use-it-or-lose-it” requirements, together with narrow definitions of eligible “uses,” can preclude environmental groups from participating in markets for natural resources. These restrictions can bias resource management in favor of extractive users, even when conservation interests are willing to pay more to protect resources from development. We argue that acquisition of public natural resource rights for the purpose of withholding them from development should be allowed. Policies should be reformed to include conservation as a legally valid form of “use.” Allowing such “nonuse rights” to public natural resources would enable markets to advance environmental goals, leading to more stable and less contentious outcomes.