A routinely applied atmospheric dispersion model was modified to evaluate alternative modeling techniques which allowed for more detailed source data, onsite meteorological data, and several dispersion methodologies. These were evaluated with hourly SO2 concentrations measured at fixed receptors around coal-fired power plants near Paradise, Kentucky, during 1976 and near Johnsonville, Tennessee, during 1977. A significant finding of the evaluation was that the more sophisticated models did not appreciably 'outperform' the routinely applied models. The models using airport meteorological data performed as well as the models using onsite wind data. With the Pasquill-Gifford and Briggs dispersion schemes, small differences in model performance were observed. More substantial differences occurred with models using onsite turbulence measurements. The model using Pasquill's recommendations tended to overpredict peak concentrations. The models based on Draxler's and Cramer's approaches using onsite turbulence yielded mixed results perhaps in part because the lateral standard deviation of wind direction available was the one-hour average of five-minute values (rather than a one-hour value) thus eliminating the longer period fluctuations that are of importance in estimating one-hour concentrations in addition to the shorter period fluctuations. Additional research is recommended to improve the application of onsite turbulence measurements and to provide more accurate estimates of plume trajectories for input to atmospheric dispersion models.