Smoking is the leading cause of preventable death and illness in the United States. National practice guidelines call for all health care providers to "ask" all patients about tobacco use, and to "advise, assess, assist, arrange" when smokers want to quit smoking (the "5 As"). Emergency departments (EDs) have not been an important locus of tobacco control efforts, although ED patients typically smoke at rates exceeding that of the general population, are interested in quitting, and often have limited access to primary care. To address the role of emergency medicine in tobacco control, the American College of Emergency Physicians convened a task force of representatives of major emergency medicine professional organizations. Funded by the Robert Wood Johnson Foundation, the group met in 2004 and 2005. This article represents a summary of the task force's recommendations for tobacco control practice, training, and research. We call on emergency care providers to routinely assess patients' smoking status, offer brief advice to quit, and refer patients to the national smokers' Quitline (800-QUIT-NOW) or a locally available program. Given the global burden of tobacco-related illness, the task force considers it essential for emergency physicians to conduct research into the efficacy of ED-based interventions and to place tobacco control into the training curriculum for emergency medicine residencies. Tobacco control fits within the traditions of other ED-based public health practices, such as injury control. ED-based tobacco control would allow the specialty to help fulfill the Healthy People 2010 mandate to reduce the prevalence of smoking among US citizens.