The paper describes a project being conducted at Case where an expert system is being used to document and develop design criteria. The objective of this project is to capture and retain design criteria knowledge, document and retrieve knowledge on-line, and predict and evaluate design criteria for new machines or new market requirements. An expert system development tool, ADS (Aion Development System), is used in this project. A system security mechanism and many graphical user interface features are implemented using object-oriented programming techniques. To facilitate knowledge acquisition, a questionnaire is also developed. The acquired knowledge has been used in several product design programs at Case.