The major objectives of the Eastern Gas Shales Project were: (1) to develop and demonstrate exploration rationales for the identification of areas within the Appalachian, Michigan and Illinois basins which offer the greatest potential for recovery of natural gas in commercial quantities; (2) to develop accurate estimates of gas-in-place and of the economically recoverable resource, and (3) to develop and demonstrate reliable and cost-effective extraction methods. The identification of potentially attractive target drilling areas and the accurate estimation of the in-place and economically-producible natural gas resource are reported. Maps, composites of geochemical parameters (total organic carbon, biofacies type, thermal alteration indexes) and stratigraphic data (thickness), combine source rock quality and thickness to identify areas in the basin with the potential for generating the greatest amounts of natural gas and oil. The most favorable prospect area is situated in southeastern Ohio, but that the entire area of eastern Ohio and northwestern West Virginia has excellent gas source potential and would be favorable for natural gas exploration. Other rich gas source and prospect areas are located in southwestern New York, north-central Pennsylvania and in northern Kentucky just west of the common boundary between Ohio, West Virginia and Kentucky. The potential oil source area of the Appalachian basin is more restricted in area extent because the generation of liquid hydrocarbons is more stringently controlled by the type of organic matter and a limited range of thermal conditions. Two areas, one centered in southeastern Ohio, but spreading laterally over most of western West Virginia and southwestern Pennsylvania and one located in southwestern New York and north-central Pennsylvania, have the richest oil source potential and, consequently, are the most favorable areas in the basin for exploration of liquid hydrocarbons.