Tuberculosis was clearly one of the most predominant diseases of the early twentieth century. At this time, Americans involved in the eugenics movement grew increasingly interested in methods to prevent this disease's potential hereditary spread. To do so, as this essay examines, eugenicists' attempted to shift the accepted view that tuberculosis arose from infection and contagion to a view of its heritable nature. The methods that they employed to better understand the propagation and control of tuberculosis are also discussed. Finally, (...) the essay explores the interpretative analyses of data that the Eugenics Record Office used in an attempt to convince contemporaries of the hereditary transmission of tuberculosis. (shrink)