This report contains the results of a technical and economic evaluation of conceptual systems for the underground mining, rubblization, and in situ retorting of deep oil shale deposits. Study efforts were first directed towards evaluation of the applicable geology, associated minerals, rock mechanics, in situ retorting, access mining, ventilation, rubblization, safety, and environmental impact factors. Conceptual systems were synthesized and then evaluated against these factors from both a technical and limited economic viewpoint. The results of these evaluations were then analyzed and, based on this analysis, two systems were selected for further study. Because of the large number of variables to be considered, a computer program was developed and utilized to provide data for the cost trade-off studies and economic analysis. Volume 1 describes the investigation and results.