Environmental tobacco smoke (ETS) exposure remains an important cause of morbidity and mortality in children. Pediatricians are well positioned to help smoking parents quit. Parents who smoke may be particularly responsive to advice to quit, repeated smoking cessation messages can be effective, and parents visit the pediatrician 8-10 times for well care in the first two years of their child's life. Yet most pediatricians do not provide smoking cessation advice. We developed a parental smoking cessation module for an established pediatric primary care decision support system (CDSS) that runs as a front-end to the Regenstrief Medical Record System. The system collects data directly from parents and guides the physician through smoking cessation counseling, using stages of change. We present the CDSS and the smoking module as well as descriptive data from our smoking cessation system. We also describe a randomized controlled trial of the system that is now underway.