The United States tar sand resource consists of an estimated 30 billion barrels of oil. Most of this resource is in six large deposits in Utah. A previous study of these areas indicates that two of these deposits (Tar Sand Triangle and Sunnyside) have a net potential recovery of 1.8 billion barrels of oil which can be realized by successful application of steam drive technology. The purpose of this report, prepared for the U.S. Department of Energy under Contract No. EW-78-C-20-0012, is to provide “Assistance in Development of Decision Criteria for DOE-EOR Project 10” which is designed to extend the applicability of the steam drive process to heavy oil reservoirs (tar sands).