The “omics” sciences might provide a biological foundation for epidemiological approaches that have previously been limited to highlighting the correlation between social factors and morbidity or mortality rates. There are those, though, that point to the risks associated with this biologization: in a “neoliberal regime of truth”, it might lead to a depoliticization of the issues related to social inequalities. In this chapter, I trace the epistemological and political history of social epidemiology from Walter B. Cannon's theory of stress in the first half of the twentieth century to the contemporary allostatic overload model. I first show that social epidemiology is an approach to social inequalities in health that is distinguished, from its onset, by an etiological model based on the physiology of stress. Second, I show that the main actors in the field understand their scientific research activities as a form of activism and thus share a moral economy of objectivity. I conclude that the risk of depoliticization does not rest in the biologizations of social inequalities in health, instead in the capacity of the actors in the field to make them an object of public debate.