A Century of the Infant Mortality Revolution is an unpublished paper. There has been rapid and widespread progress in reducing infant mortality over the last 100 years. In 1900, there was only one country worldwide where we know that infant mortality was below ten percent. A century later, out of the 187 countries for which we have data, only nineteen had an infant mortality rate of above ten percent. Better health outcomes have been achieved at lower incomes to the extent that income growth appears to be a minor factor in determining the course of the infant health transition. Instead, factors related to global progress appear to have been key –probably related to the spread of knowledge and cheap technologies. Only state collapse or health shocks as dramatic as the AIDS epidemic appear powerful enough to considerably slow this rate of progress.