This chapter discusses consequences of a type of preventive medicine from the social standpoint that, paradoxically, aimed to reduce chronic disease through the individualization of health care responsibility. It examines how the influence of social science helped to develop a new managerial ethos in preventive medicine that focused on individual lifestyles as the source of social health. This approach starkly contrasted the political solutions of nineteenth-century state medicine or sanitary reform to population health improvement. The chapter explores how these developments were paralleled by a new commercialization of individual health. State and public health authorities did not have a monopoly in producing strategies for creating healthy populations in the most affluent societies in history. One of the most powerfully symbolic representations of the epidemiological transition at the turn of the twentieth century was the predominance of tuberculosis.