Managed care organizations are in an excellent position to implement population-based, as well as patient-centered, approaches to reduce behavioral risk factors associated with major chronic diseases. Group Health Cooperative of Puget Sound employed a population-based model for smoking that contributed to a decrease from 25% to 15.5% in smoking prevalence in 10 years among its more than 550,000 adult enrollees in western Washington. This model may have application to other arenas where health systems can support beneficial behavior change.