Smoking is one of the most important modifiable causes of poor pregnancy outcomes in the United States. An office-based protocol that systematically identifies pregnant women who smoke and offers treatment has been proven to increase quit rates. For pregnant women who are light to moderate smokers, a short counseling session with pregnancy-specific educational materials often is an effective intervention for smoking cessation. The 5 A's is an office-based intervention developed for use by trained practitioners. Techniques for smoking reduction, pharmacotherapy, and health care support systems can help smokers quit.