This paper uses unique historical data from Denmark to estimate the effects of the introduction of a universal home visiting program for mothers and their infants from 1937 through 1949. To identify the effects of the program on infant survival rates, the paper exploits exogenous variation in the timing of program implementation across municipalities. Using data for all Danish towns, I find a significant and positive effect on infant survival rates of around 0.5-0.8% or around 5-8 lives saved per 1000 live births at the mean infant survival rate for the period. The program was effective in the great majority of relatively small Danish towns of the time, where the treatment constituted the first large-scale and publicly funded initiative to combat infant mortality. My main finding is robust to the inclusion of town-specific time trends, the control for time-varying socio-economic town characteristics, and the omission of towns with potentially confounding efforts to fight infant mortality. Using complementary data at higher levels of aggregation, I find some indication for the program contributing to the decrease of mortality from acute enteritis, a major cause of infant death at the time. This finding suggests that an important mechanism behind the program's effect was the nurses' promotion of breastfeeding and proper infant nutrition. Finally, a stylized analysis of the costs of the home visiting program shows that they were modest when compared to estimates from similar contexts, namely, home visiting in the U.S. and clean water supply. Future research should use comprehensive Danish register data to examine potential long-run returns to home visiting.