The report gives results of activities relating to the Advanced Utility Simulation Model (AUSM): sensitivity testing, comparison with a mature electric utility model, and calibration to historical emissions. The activities were aimed at demonstrating AUSM's validity over input variable ranges likely to be used for application runs. Univariate sensitivity tests demonstrated that AUSM runs and returns credible results for input ranges expected during model application and addressed issues raised by reviewers. AUSM was compared with Coal and Electric Utilities Model (CEUM) for EPA's 1987 interim base case to compare results and analyze reasons for differences between the output of the two models for 1990 through 2010. Experiments for 1980 through 1985 found ways to calibrate the model to historical emissions without resorting to scaling or ad hoc methods. All three activities resulted in increased confidence in AUSM for several reasons: AUSM worked well over a wide range of values; sensitivity tests and normal model inputs span such a wide range of possible values that the model will clearly work for any expectable set of inputs; outputs changed in directions and by magnitudes which were consistent with input changes and with analysts' understanding of electric utilities; and all outputs form a consistent set of results.