Load forecasting plays an important role in the electric power industry. Similar to many other industries that need demand forecasts, forecasting the electricity demand of the special days, such as holidays and their surrounding days, has been a challenging problem. Since the holiday effect often varies from one region to another, a specific model developed for one utility may not be suitable for another. This presentation will introduce a regression-based approach to model the holiday effect of electricity demand, followed by the comparative studies of ten utility systems.