Grants from the Illinois Department of Energy and Natural Resources and the U.S. Department of Energy partially supported an integrated geological, geophysical, and engineering research project that defined the architecture, rock, mineral, and fluid properties of two hydrocarbon-bearing formations in 15 Illinois oil fields. This research has established the kinds of data and techniques needed for optimal reservoir characterization assessment and management in Illinois. Results of the project are presently being applied to improve reservoir management and recovery of hydrocarbons from Illinois Basin reservoirs. Improvement in oil recovery will continue, provided technology transfer is adequate, research is continued, and research results are effectively applied.