Geothermal resource assessments have been an integral part of developing a geothermal resource ever since the industry began producing power. Such an effort is the rst step in deciding whether investment in a facility is an economically viable undertaking. However, to better understand the magnitude of the geothermal resource base and the ability of this energy source to contribute to local, regional, or national energy markets, it is necessary to develop a more systematic analysis than is usually pursued when considering the development of a single facility.