Phase I results of a CO2-assisted or recovery demonstration project in selected Cypress Sandstone reservoirs at Mattoon Reid, Illinois are reported. The design and scope of this project included CO2 injectivity testing in the Pinnell and Sawyer units, well stimulation treatments with CO2 in the Strong unit, and infill well drilling, completion and oil production. The field activities were supported by extensive CO2-oil-water coreflood experiments, CO2-oH phase interaction experiments, and integrated geologic modeling and reservoir simulations. The progress of the project was made public through presentations at an industry meeting and a DOE's con1ractors'symposium, through quarterly reports and one-to-one consultations with interested operators. Phase II of this project was not implemented. It would have been a water-alternating-gas (YVAG) project of longer duration.