The US Department of Energys̀ (DOE) Office of Civilian Radioactive Waste Management (OCRWM), created with the enactment of the Nuclear Waste Policy Act of 1982 (NWPA), is tasked to accept and dispose of the nations̀ high-level radioactive waste and spent nuclear fuel in a deep geologic repository (high-level radioactive waste program). The report summarizes significant site characterization activities during the period from April 1, 1997 through September 30, 1997, in the evaluation of Yucca Mountain as a potential site for the geologic disposal of spent nuclear fuel and high-level radioactive wastes. The progress report also cites technical reports and research products that provide the detailed information on these activities. Chapter 2 outlines technical and regulatory issues that must be addressed by the Project and planned work toward achieving future objectives concerning the viability assessment, the environmental impact statement, the site recommendation, and the license application. Chapter 3 describes technical progress in preclosure radiological safety analysis, postclosure performance assessment, and performance confirmation activities. Chapter 4 describes various aspects of repository and waste package design and construction. It also discusses the Exploration Studies Facility cross drift. Chapter 5 describes site characterization activities, and Chapter 6 contains a complete list of references.