Technical uncertainties remaining in the UCG technology include specific criteria for site selection, large-scale burn interactions, details of process control, multiple well operation, overall system reliability, subsidence, and water quality effects. Considerable effort has been expended on understanding and controlling the process, on predicting and mitigating subsidence, and on maintaining water quality. Some data are available on site acceptability, but as yet information from large-scale field tests are not in the public domain. Commercialization of UCG will not be possible until such data become available. A program plan to commercialize UCG in an orderly, paced manner has been developed. The program would cost $200 million over seven years, some of which could be cost-shared with industry. The proposed program includes development of a more detailed program plan. The laboratory component of the program, although only a small fraction of the budget, is crucial. It contains environmental research, modeling, experimental studies, economic and system studies, instrumentation development, and materials studies. The field component includes UCG of both flat and steeply dipping coal beds as well as of less tractable bituminous coal. The field projects involve development of criteria for site selection and characterization, large block tests in bituminous coal, simple, small-scale field tests, subsequent more complex and longer-running tests, and finally large scale, or pilot tests. Steam-oxygen gasification would probably be used. 48 references, 11 figures, 6 tables.