Through a case study of one higher-education institute, two historical moments are narrated through genealogy in order to expose the contentious historical roots of the discourse of critical thinking. Two moments in time when critical thinking curriculum surfaced within institutional discourse are located in order to addresses the material impacts of this discourse within institutional change. I excavate a particular, tenuous history of critical thinking, showing its use in navigating seemingly incompatible relationships between disciplinary-bound knowledge, student service, and academic legitimacy. This paper provides an illustration of how genealogy can be used to reconceptualize curriculum history and theory, not simply in accounting for curriculum over time, but in destabilizing the taken-for-grantedness of its overarching concepts. Thus, rather than contending with what critical thinking may be, this genealogy addresses the how of critical thinking, through excavating its when