AbstractThis paper develops a performativist metaphysical grounding of NPM‐based performance measurement as a radical alternative to a representationalist grounding, an alternative that turns performance measurement on its head. Performance measurement turns from an act of representation characterized by a metaphor of reflection into an ethical practice of mattering characterized by a metaphor of diffraction. In performativism, performance measurement does not (imperfectly) represent performance as a base for knowing and intervention from afar (both in terms of space and time) but issomehowperformative ofwho and what come to countin the world. Its exclusionary character makes it an inherently ethical practice. We contrast a performativist grounding of performance measurement with a representationalist grounding and rework concepts of responsibility and accountability. We illustrate a performativist grounding of performance measurement with examples from academia and healthcare and provide a direction for future research.