We analyze the cost of enforcing a system of firm specific emissions standards vis a vis a transferable emissions permit system in the context of complete and incomplete information. We also examine the optimality of a transferable emissions permit system when abatement costs and enforcement costs are considered. We show that under incomplete information, regulation based on each firm-specific emissions standards cannot be less costly than a transferable emissions permit system. In addition, we found that the distribution of emissions that minimize aggregate program costs differ from the distribution of emissions generated by a competitive transferable emissions permit system.