Presentism is the thesis that everything is present, which implies that there are no past (or future) things or events. It is sometimes said to be imcompatible with the claim that every truth must have some ground on being. In this paper, I will examine the efficacy of such an argument in favor of presentism. In my view, however, how to respond to the grounding objection depends on what kinds of past truths we deal with: (i) truths about how present things were, (ii) general truths about things that no longer eixst, and (iii) singular truths about wholly past things. Before discussing this, I will also give an overview of the grounding project.