During the past three years laboratory studies have been conducted on Texas lignite to determine combustion and gasification products as a function of pressure and temperature. More recently, the scope of the program has been expanded to include mathematical modeling and field testing. A numerical model has been developed which predicts gas composition and flame front velocity. The model has been validated by simulation of laboratory combustion tube experiments on Texas lignite. The model and laboratory experiments were used to design a field test on underground lignite gasification in the Yegua formation in Brazos County, Texas. In addition, the model has been used to make parametric studies.