Thermal analysis was applied to Green River Formation oil shales to demonstrate the method's capabilities for estimating oil yields and for determining dawsonite, nahcolite and nordstrandite. A single sample heated in thermal analysis apparatus incorporating differential thermal analysis (DTA) and thermogravimetry (TG) will produce quantitative data on the three oil shale minerals and excellent oil yield estimates. Coefficients of determination (R/sup 2/) ranged from 0.88 for dawsonite and nordstrandite determinations to 0.998 for nahcolite. Requirements to be met by thermal analysis equipment to obtain accurate oil-shale compositional data are outlined. The method is especially useful where minerals are encountered that interfere with other analyticl techniques.