Economic models are used to show the extent of the difficulties involved in monitoring and enforcing pollution control laws on a continual basis. The authors make several recommendations for policy change. They also show that high rates of compliance can be achieved within tight budget constraints.Originally published in 1986'The authors attempt to bring to earth much of the environmental literature that implicitly assumes pollutant dischargers will comply with environmental laws regardless of their self-interest and that violators are discovered and punished-reality holds otherwise.'Energy Review