To the Editor, We want to thank Christopher Davis, Victoria Lazariu and Jackson Sekhobo for their detailed comments on our paper, ‘‘Maternal Smoking and the Timing of WIC Enrollment.’’ We provide a point-by-point response to their key comments below. However, before responding in detail, we would like to explain why we choose to examine an association between the timing of WIC enrollment and smoking. Our rationale goes to the heart of a larger exchange, which we would like to encourage among readers of this journal: whether a supplemental nutrition program that provides relatively modest calorie, protein and micronutrient supplements to pregnant women is likely to have a meaningful effect on birth outcomes in a developed country like the US. Let us be clear from the beginning. We are concerned with a single vein of research about the WIC program: the association between prenatal WIC participation and birth outcomes. We believe WIC plays an essential role in the distribution of infant formula and nutritional enhancements for young children. We also believe the Program struggles honestly with the challenging task of simultaneously encouraging breastfeeding while at the same time ensuring poor and near-poor infants have sufficient milk. But in our role as academics and researchers, we seek to understand what aspects of the Program really work and how WIC might better leverage its interactions with poor and nearpoor pregnant women to improve maternal, infant, and child health in long run. Our story begins in 2005 with an article published by one of us (Joyce) in the Journal of Policy Analysis and Management. The authors argued in that initial article that the association between WIC and lower rates of low birth weight had been greatly overstated in much of the academic literature. In past studies, researchers have assumed that WIC affected birth weight by lowering both the risk of preterm birth and fetal growth retardation. Although researchers acknowledged there existed what is termed gestational age bias, there was still the belief that nutritional supplementation lowered the incidence of preterm birth. Yet even a cursory review of the clinical literature reveals just how little is known about the etiology of preterm birth and how difficult it has been to discover the means by which to try and prevent it. Thus, the conclusion that prenatal WIC participation was associated with or could reduce the risk of very preterm birth (\32 weeks gestation) by 50% as reported in a C. Yunzal-Butler Department of Economics (Alumnus), Graduate Center, City University of New York, 365 Fifth Ave, 5th Floor, New York, NY 10016, USA e-mail: cyunzal@gmail.com