This report summarizes work over the past twelve months on DOE Contract DE-AC21-92MC28138, Development of a Natural Gas Systems Analysis Model (GSAM). The products developed under this project directly support the Morgantown Energy Technology Center (METC) in carrying out its natural gas R&D mission. The objective of GSAM development is to create a comprehensive, non-proprietary, microcomputer model of the North American natural gas system. GSAM explicitly evaluates the key components of the system, including the resource base, exploration and development practices, extraction technology performance and costs, project economics, transportation costs and restrictions, storage, and end-use. The primary focus is the detailed characterization of the resource base at the reservoir and subreservoir level. This disaggregation allows direct evaluation of alternative extraction technologies based on discretely estimated, individual well productivity, required investments, and associated operating costs. GSAMS design allows users to evaluate complex interactions of current and alternative future technology and policy initiatives as they directly impact the gas market. GSAM development has been ongoing for the past four years. The project is currently implementing the recommendations of an industry Peer Review Committee. Research findings to date have focused the design work on critical data and model segments required to fully evaluate future market conditions. The contract also includes the development, testing, and integration of an environmental analysis module, including data development, analytical methodology, and full integration into GSAM. This work is currently being completed in coordination with DOEs Metairie Site Office (MSO). The full development of GSAM also now includes the finalization of reservoir level databases. Data development is complete with enhancements for key regions and resource segments having been implemented.