The focus of this paper is to present a classification methodology for evaluating the complexity of expert systems. Complexity in the area of expert systems consists of two basic dimensions: the complexity of the underlying knowledge residing with the experts and the complexity of the technology incorporated into a given system. The classification methodology was developed and tested for its ability to accurately differentiate expert systems with a pilot sample of six expert systems. Using this approach provides a basis for managers to assess the complexity of a particular expert system and thereby assist in planning the scope of the development and implementation effort and the "fit" of a particular project with the firm's internal resources and the needs of its competitive environment.