We tested the efficacy of a cognitive-behavioral intervention in reducing environmental tobacco smoke exposure (ETSE) and improving pregnancy outcomes among black women. We recruited 1044 women to a randomized, controlled trial during 2001-2004 in Washington, DC. Data on 691 women with self-reported ETSE were analyzed. A subset of 520 women with ETSE and salivary cotinine levels (SCLs) of <20 ng/mL were also analyzed. Individually tailored counseling sessions, adapted from evidence-based interventions for ETSE and other risks, were delivered to the intervention group. The usual-care group received routine prenatal care as determined by their provider. Logistic regression models were used to predict ETSE before delivery and adverse pregnancy outcomes. Women in the intervention were less likely to self-report ETSE before delivery when controlling for other covariates (odds ratio [OR]: 0.50 [95% confidence interval (CI): 0.35-0.71]). Medicaid recipients were more likely to have ETSE (OR: 1.97 [95% CI: 1.31-2.96]). With advancing maternal age, the likelihood of ETSE was less (OR: 0.96 [95% CI: 0.93-0.99]). For women in the intervention, the rates of very low birth weight (VLBW) and very preterm birth (VPTB) were significantly improved (OR: 0.11 [95% CI: 0.01-0.86] and OR: 0.22 [95% CI: 0.07-0.68], respectively). For women with an SCL of <20 ng/mL, maternal age was not significant. Intimate partner violence at baseline significantly increased the chances of VLBW and VPTB (OR: 3.75 [95% CI: 1.02-13.81] and 2.71 [95% CI: 1.11-6.62], respectively). These results were true for mothers who reported ETSE overall and for those with an SCL of <20 ng/mL. This is the first randomized clinical trial demonstrating efficacy of a cognitive-behavioral intervention targeting ETSE in pregnancy. We significantly reduced ETSE as well as VPTB and VLBW, leading causes of neonatal mortality and morbidity in minority populations. This intervention may reduce health disparities in reproductive outcomes.