The Upper Cretaceous Lewis Shale of the San Juan Basin, Colorado and New Mexico, has an enormous gas-in-place volume. This report describes formation evaluation efforts and a literature review pertaining to reservoir properties of the Lewis Shale. Detailed analysis of data from three cooperative research wells belonging to Energen Resources Inc. and Burlington Resources Inc. is documented. Most data is included in extensive appendix files. Log analysis models were developed to estimate the volume of gas stored by sorption, compression, and solution. Gas-in-place volumes and in situ gas permeability were quantified. Ranges in possible gas recovery volumes were estimated. The formation evaluation approach implemented and documented during this project will assist operators in understanding this unconventional resource and in the commercial exploitation of the Lewis shale and the other similar Rocky Mountain region shale gas reservoirs that possess potential for very large gas resource volumes.