Incorporated in Pro/ENGINEER 2000i software, behavioral modeling technology allows engineers and designers to specify and solve design problems directly in their computer-aided design (CAD) systems. Traditional CAD systems record only the geometry of a part, while the task of meeting design specifications and finding the best solution is performed separately in analysis and optimization applications, if at all. Using this new functionality, designers state the goals of their proposed design, then let their CAD systems optimize those parameters and arrive at potential solutions as sets of 3-D solid models. This integration and automation of the entire design process provides engineers with the flexibility to explore many more design options than were ever possible in the past. Brian Duckering, product manager for behavioral modeling at Parametric Technology, says that in current practice, designs are manually evaluated (often requiring physical prototypes), then changed by trial and error until considered "close enough." With this technology, the resulting "smart" CAD models encapsulate engineering intelligence, containing design criteria, goals, constraints, and evaluation information. From this rich bundle of knowledge, Behavioral Modeling makes it simple to explore exactly how design goals are impacted by geometric changes, find design configurations worth considering, determine values of design variables required to solve specific problems, and, ultimately, generate the very best design in the shortest amount of time. John Teresko, John Sheridan, Tim Stevens, Doug Bartholomew, Patricia Panchak, Tonya Vinas, Samuel Greengard, Kristin Ohlson, and Barbara Schmitz contributed to this article.