Many philosophers believe that truth is grounded: True propositions depend for their truth on the world. Some philosophers believe that truth’s grounding has implications for our ontology of time. If truth is grounded, then truth supervenes on being. But if truth supervenes on being, then presentism is false since, on presentism, e.g., that there were dinosaurs fails to supervene on the whole of being plus the instantiation pattern of properties and relations. Call this the grounding argument against presentism. Many presentists claim that the grounding argument fails because, despite appearances, supervenience is compatible with presentism. In this paper, I claim that the grounding argument fails because, despite appearances, truth’s grounding gives the presentist no compelling reason to adopt the sort of supervenience principle at work in the grounding argument. I begin by giving two precisifications of the grounding principle: truthmaking and supervenience. In Sect. 2, I give the grounding argument against presentism. In Sect. 3, I argue that we should distinguish between eternalist and presentist notions of grounding; once this distinction is in hand, the grounding argument is undercut. In Sect. 4, I show how the presentist’s notion of grounding leads to presentist-friendly truthmaking and supervenience principles. In Sect. 5, I address some potential objections.