The “quantified self,” a cultural phenomenon which emerged just before the 2010s, embodies one critical underlying tenet: self-tracking for the purpose of self-improvement through the identification of behavioral and environmental variables critical to one’s physical and psychological makeup. Of course, another project aimed at systematically improving persons through changes to the greater population is eugenics. Importantly, both cultural phenomena are built on the predictive power of correlation and regression—statistical technologies that classify and normalize. Still, a closer look at the late-nineteenth and early-twentieth century eugenic projects and the early-twenty-first century proliferation of quantified self devices reveals an inherent incommensurability between the fundamental tenets underlying each movement. Eugenics, with its emphasis on hereditary physical and psychological traits, precludes the possibility that outside influences may lead to changes in an individual’s bodily or mental makeup. The quantified self, on the other hand, is predicated on the belief that, by tracking the variables associated with one’s activities or environment, one might be able to make adjustments to achieve physical or psychological health. By understanding how the technologies of the two movements work in the context of the predominant form of Foucauldian governmentality and biopower of their respective times, however, the incommensurability between these two movements might in fact be resolved.