We study the cost-effectiveness of inducing compliance in a program that caps aggregate emissions of a given pollutant from a set of heterogeneous firms based on emissions standards and the relative cost-effectiveness of such a program with respect to an optimally designed program based on tradable discharge permits. Our analysis considers abatement, monitoring and sanctioning costs, as well as perfect and imperfect information on the part of the regulator with regard to the polluters’ abatement costs. Under perfect information we find that (a) the total-cost-effective design of a program based on standards is one in which the standards are firm specific and perfectly enforced, and (b) the total cost of an optimally designed program based on standards is lower than the total cost of an optimally designed transferable emission permits system, except under special conditions. This is true when it is optimum to induce perfect compliance and when it is not. Under imperfect information, nevertheless, it is only by implementing a system of tradable permits and perfectly enforcing it with a constant marginal penalty tied to the price of the permits, that the regulator can surmount the informational problem and at the same time minimize the total cost of the program with certainty.