Continued high rates of smoking among socioeconomically disadvantaged women lead to increases in children's health problems associated with exposure to tobacco smoke. The pediatric clinic is a "teachable setting" in which to provide advice and assistance to parents who smoke. To evaluate a smoking cessation intervention for women. Two-arm (usual care vs intervention) randomized trial. Pediatric clinics serving an ethnically diverse population of low-income families in the greater Seattle, Wash, area. During the clinic visit, women received a motivational message from the child's clinician, a guide to quitting smoking, and a 10-minute motivational interview with a nurse or study interventionist. Women received as many as 3 outreach telephone counseling calls from the clinic nurse or interventionist in the 3 months following the visit. Self-identified women smokers (n = 303) whose children received care at participating clinics. Self-reported abstinence from smoking 12 months after enrollment in the study, defined as not smoking, even a puff, during the 7 days prior to assessment. Response rates at 3 and 12 months were 80% and 81%. At both follow-ups, abstinence rates were twice as great in the intervention group as in the control group (7.7% vs 3.4% and 13.5% vs 6.9%, respectively). The 12-month difference was statistically significant. A pediatric clinic smoking cessation intervention has long-term effects in a socioeconomically disadvantaged sample of women smokers. The results encourage implementation of evidence-based clinical guidelines for smoking cessation in pediatric practice.