Historically, public health workers, physicians, and reformers have used the infant mortality rate as an indicator of the goodness of a society—its general welfare, the justness of its political system, the efficacy of its public works, the benevolence of its powerful; a high rate of death among the very young was an index of a community's shame. These views of the infant mortality rate as reflecting general characteristics of a society were widely displayed in the second half of the nineteenth century even as most disease entities were becoming more narrowly defined and ordinarily linked not to the nature of society or individual predisposition but to specific pathological organisms. Using Philadelphia as a case study, we examine the history of the infant mortality rate from 1870 through 1920, both the technical aspects of its calculation and its use as an indicator of broad societal problems and a catalyst for policy. Our emphasis is not on explaining the trends in the death rates of the very young but on the uses and meanings given to the infant mortality rate during the second half of the nineteenth century and the first decades of the twentieth century specifically as they related to three efforts to lower infant death rates—removing infants from the city, improving the supply of milk, and establishing child hygiene programs.