In 2008, Timmermans and Haas called for a sociology of disease to develop and challenge the sociology of health and illness. A sociology of disease, they argued, would take seriously the biological and physiological processes of disease in theorising health and illness. Building on two decades of Science and Technology Studies and feminist work on biological actors such as hormones and genes, we propose a cortisol sociology to push further at this argument. As a ‘messenger of stress,’ cortisol is key to understanding human and non-human health as a biosocial phenomenon. We argue that sociologists should engage with cortisol through critical yet open-minded reading of the relevant science and critical triangulation studies, and by tracking cortisol’s movements from science into public worlds of biosensing and self-monitoring.