Exploration for hot dry rock (HDR) as a potential geothermal resource presents some novel problems and unusual contradictions not to be expected in exploration for other geological resources. This became apparent at a meeting held on June 22, 1976, at Los Alamos Scientific Laboratory (LASL) on t he subject of Exploration Methods for Hot Dry Rock. Unlike the case of petroleum or mineral prospecting the search for HDR is not for a region of strong chemical contrasts that are displayed as contrasts of physical properties. Rock suitable for HDR technologies has relatively weak geological manifestations and is almost geophysically invisible on a local scale; it is not so susceptible to direct detection as is, say, a gas reservoir. Thus we must look at related manifestations and for patterns more than for hot dry rock itself.