ABSTRACT Environmental impact statements (EISs) are often required under the National Environmental Policy Act or similar state laws for proposed activities such as petroleum exploration and production or for new oil transportation facilities such as marine terminals and pipelines. One of the critical concerns which must be properly addressed in an EIS for such activities or facilities is the risk of an accidental oil spill and the environmental impact which would result. This paper describes a comprehensive approach to analysis of oil spill accidents in such EISs. It identifies sources of relevant data and technical information while also pointing out areas where knowledge is incomplete. Techniques are recommended for determining the probability and size of a spill, the fate of the oil, and the resulting environmental impacts. The paper is intended to serve as a useful guide for those preparing or reviewing EISs for proposed large projects which involve appreciable oil spill risks.