This paper is an update and review of natural resource damage assessment (NRDA) and restoration under the US Oil Pollution Act of 1990. The paper is a review and overview of the damage assessment process, as well as descriptions of efforts being taken to further refine that process and encourages more cooperative work in the future. It also presents two case studies (The World Prodigy oil spill that occurred in June of 1989, and restoration projects that began in 1996 and the Lake Barre oil spill which occurred in May of 1997, with restoration projects beginning in the summer of 2000.) demonstrating the current NRDA approach. (C) 2002 Published by Elsevier Science Ltd.