A major challenge delaying the significant expansion of geothermal energy production, compared to the surge over the past decade in other renewable sources such as wind and solar, has been the lack of a coherent and universally adopted standard for assessing the potential of geothermal resources. Although some strong analogies with petroleum industry practice can be drawn, geothermal heat is a fundamentally different type of resource from hydrocarbon resources. Its diffuse nature in sedimentary rocks, strongly process dependent recovery characteristics and extensive deep seated and serendipitous magmatic origin make it hard to quantify in terms familiar to petroleum engineers. Efforts are underway within the SPE to produce a standard for evaluation of geothermal resources equivalent to the Petroleum Resource Management System (PRMS). A discussion at this session on this subject will be both timely and helpful towards the transfer of petroleum industry related technology and skills and the identification of gaps in those technologies and skills that remain to be filled in order to meet the geothermal resources evaluation challenge.