Successive field tests of UCG conducted at a single site have shown a serious lack of reproducibility which presents serious problems for the design of any plant built to utilize the gas produced. Cost precludes the use of many pilot tests to more carefully define the plant design basis. It is shown in this paper how relatively inexpensive laboratory tests along with the use of mathematical models and data from at least one two well pilot test can be used to provide a better design basis for scale up to commercial production.