A randomized controlled trial study design was used to investigate the effectiveness of a Healthy Families America model prenatal intervention for increasing breastfeeding rates among Latina immigrants residing in an impoverished New York City community. Exposure to the intervention did not affect mother report of any breastfeeding (ABF) during the first week postpartum, but it did affect mother report of exclusive breastfeeding (EBF). Thirty-two percent (44/137) of mothers exposed to the intervention reported EBF during the first week postpartum compared to 20% (20/101) of mothers not exposed to the intervention (odds ratio 1.92; 95% confidence interval 1.05-3.52). This positive effect of the intervention on EBF remained statistically significant after controlling for the negative effect of household income on EBF (adjusted odds ratio, 1.89; 95% confidence interval, 1.02-3.50). Additional research is needed on the effectiveness of breastfeeding promotion programs targeting low-income Latinas.