In recent decades several researchers have investigated the relationship between corporate environmental performance and environmental disclosures. A number of these studies have also investigated the positive/negative content of the disclosures, particularly following the occurrence of negative environmental events or media coverage. Limited research has investigated the usefulness of regulated public external disclosures of corporate environmental performance information as a driver of annual report environmental disclosure behaviour. The mandatory Austtalian National Pollutant Inventory now provides interested parties with access to information on corporate pollution emissions. This represents a change to the corporate operating environment and represents a potential threat to corporate legitimacy. This paper reports the results of research investigating the release of corporate pollution emission information on the National Pollutant Inventory and changes in corporate environmental disclosures in annual reports.