||Since their introduction in the eighties, Computer-Aided Drafting (CAD) systems have becomeubiquitous among design engineers. From costly systems with simple interactive geometric capabilities, CAD-systems have evolved into affordable, but sophisticated tools which automatemany aspects of design documentation and retrieval. The development of even routine designs,however, has still been a manual - and often tedious - process. These first generation CAD toolshave provided gains in drafting productivity of 50% to 200% in repetitive design applications.This article describes the history and evolution of a new kind of knowledge-based CAD system,Design++. By providing significant new capabilities to support both the development and documentation of design solutions, Design++ increases productivity in design projects by ten to fifteentimes, freeing engineers to make fuller use of their skills and creativity.Design" allows storage and re-use of engineering knowledge, supports engineering teamworkand concurrent engineering, enables "what-if' experimentation, integrates engineering disciplines, and automates generation of documents, including drawings, parts lists and specifications.Keywords: Knowledge-Based CAD, Intelligent CAD, Knowledge-Based Engineering System,Engineering Expert System, Design Automation.