Existing computer software for EMC analysis can be divided into three categories. Analytical modeling codes employ closed form expressions to solve problems of general interest to EMC engineers or circuit designers. Numerical modeling codes use numerical techniques to solve Maxwell's equations subject to specific boundary conditions. EMC rule checkers search a design for features that violate basic EMC design guidelines. This paper outlines the relative advantages and limitations of each of these three approaches and describes an expert system EMC modeling approach. The new approach combines analytical models, numerical models, and EMC rule-checking in order to evaluate designs in much the same way that an EMC expert would.