The oil-shale production cost estimates reported by the National Petroleum Council in Dec. 1972, as part of an overall study of the U.S. energy situation are the most recent publicly available data on oil-shale economics. Using the basic NPC costs, this study examines several important parameters affecting shale oil's economic viability. Other factors pertinent to consideration of oil shale as a domestic fuel source, such as the leasing of federal oil shale lands, water availability, and environmental restraints are reviewed.