This project evaluated the QuitAssist™ Web site, a smoking cessation resource site developed and maintained by Philip Morris USA. The evaluation involved six studies, ranging from a large-scale survey to a usability analysis involving smoking cessation and Web design experts. If the evaluation finds that this Web-based resource facilitates smoking cessation, it will motivate additional studies of the Web as a means of producing change in health behavior. Although the grant was officially awarded to the Duke Center for Nicotine and Smoking Cessation Research, the majority of the funds are administered through the Center.