An expert system is a computer software technology developed from artificial intelligence research. It may be used for intelligent manufacturing process control and, when properly designed, has the capability to imitate human behavior. An expert system's value is to assist a human in executing realtime process control decisions in a complex system. This article provides an introduction to the concepts of intelligent process control and includes a process control scenario applying an expert system as well as statistical and optimization technologies. A simple guide of how to get started and a description of expert system tools are also presented. © 1991 TMS.