This study compares the incidence of low birth weight among mothers enrolled in Arizona's Health Start program to a sample of non-Health Start mothers with similar medical and social risk factors. A quasi-experimental design was used to match Health Start program participants to non-participants on the basis of similar medical and social risk factors. Health Start program data were linked to birth certificate data to create a sample of 5,480 pregnant women. A logistic regression analysis was conducted to predict the likelihood of having a normal birth weight (i.e., 2,500 g or more). The findings indicate that Health Start mothers had twice as better odds of having a normal birth weight than non-Health Start mothers, even after controlling for gestational age, adequacy of prenatal care, mother's history of preterm birth, weight gain during pregnancy, alcohol and cigarette use, mother's age, education and residency. Hispanic women in the program were three times as likely to have a normal birth weight baby when compared to Hispanics who were not in the program and twice as likely as non-participant Whites. And lastly, women in urban settings had better birth outcomes, especially Hispanic women. Evidence suggests that newborn infants of mothers enrolled in the Health Start Program had better birth weight outcomes even after controlling for the effects of possible confounders. However, the program seems to affect Hispanics and non-Hispanic Whites differently; in particular, Hispanics who are in the program demonstrated the best birth outcomes. One possible explanation for the general success of the program could be that program participants reported lower cigarette use during pregnancy. A limitation of this study is that that there could be reporting bias on the part of Health Start participants about their risks to enter into the program, which is difficult to verify.