Although 78% of smokers report that a health professional has previously advised them to quit smoking, most smokers are not advised to stop smoking or offered assistance with smoking cessation during a given ED visit. There are multiple barriers to routine implementation of smoking cessation guidelines by emergency clinicians, however, and rigorously performed clinical trials are needed to demonstrate that routine screening and counseling of ED patients results in increased quit rates. To determine the feasibility of implementing the Agency for Healthcare Research and Quality (AHRQ) Smoking Cessation Guideline in the ED, we will conduct a clinical trial in 974 ambulatory adult smokers who present to 2 emergency departments, using a pre-post design. During the 3-month baseline period, clinicians will perform their usual duties but will not receive training in use of the AHRQ Guideline. Based on the Chronic Care Model, the 3-month intervention period will include: 1) a tutorial on brief cessation counseling for ED nurses and physicians, 2) use of an ED algorithm that includes recommended tobacco counseling items, 3) fax referral of motivated smokers to Quitline Iowa for proactive telephone counseling plus free nicotine replacement therapy, and 4) group and individual feedback to ED staff. We will conduct exit interviews of ED patients to assess performance of guideline-recommended actions by ED staff and 3- and 6-month telephone follow-up to determine 7-day point-prevalence abstinence (with biochemical confirmation of self-reported quitters at 6 months). Our main analyses will examine the contrast between the intervention and control periods in the performance of guideline-recommended actions and in 6-month quit rates, using hierarchical logistic regression to adjust for baseline differences in potentially confounding patient variables. In secondary analyses, we will assess the change in attitudes of ED nurses and physicians toward smoking cessation counseling. This feasibility study will determine the receptivity of patients and ED staff to the guideline-based intervention and will provide estimates of effect size in planning a full scale multi-site clinical trial of the study intervention in community hospital EDs.