We estimate the impact of participation in Chile Crece Contigo (ChCC), Chile’s flagship earlylife health and social welfare program, on neonatal health outcomes. We use administrative birth data matched to social benefits usage, and the staggered program roll-out, to identify the impact of participation. We find that this targeted social program had significant effects on birth weight (approximately 10 grams) and other early life human capital measures. These benefits are largest among the most socially vulnerable groups, however shift outcomes toward the middle of the distribution of health at birth. We show that program is efficient when compared to other successful neonatal health programs around the world, and find some evidence to suggest that maternal nutrition components and increased links to the social safety net are important mechanisms of action.