This recently released 90-page report by the US Geological Survey and the US Fish and Wildlife Service is a summary of previously reported and currently updated research on the potential biological impacts of petroleum exploration and development in the Arctic National Wildlife Refuge (ANWR). After a 1987 report to Congress recommending opening the refuge to "an orderly oil and gas leasing program," but cautioning that "adverse effects to some wildlife populations were possible," scientists continued to study potential impacts on caribou, polar bear, and muskox populations and habitat. This update includes new information about impacts that potential development may have on the Porcupine Caribou Herd. Although the report is written for a technical audience, the current congressional debate about petroleum development in ANWR may make this report of interest to a general audience.