Abstract An implication of the Coase theorem is that under certain conditions, the market equilibrium in a cap-and-trade system will be cost-effective and independent of the initial allocation of tradable rights. That is, the overall cost of achieving a given aggregate emission reduction will be minimized, and the final allocation of permits will be independent of the initial allocation. We call this the independence property. This property is important because it means that the government can establish the overall pollution reduction goal for a cap-and-trade system by setting the cap and leaving it up to the legislature to construct a constituency in support of the program by allocating the allowances to various interests without affecting either the environmental performance of the system or its aggregate social costs. We examine the conditions under which the independence property is likely to hold—both in theory and in practice.