Abstract According to priority monism, there are many concrete entities and there is one, the cosmos, that is ontologically prior to all the others. I begin by clarifying this thesis as well as its main rival, priority atomism. I show how the disagreement between the priority monist and atomist ultimately turns on how the thesis of concrete foundationalism is implemented. While it's standard to interpret priority monism as being metaphysically noncontingent, I show that there are two competing, prima facie plausible conceptions of metaphysical necessity—the essence‐based and law‐based conceptions—on which it is reasonable to view its modal status differently. This, I suggest, is good for the priority monist—various objections to the thesis presuppose that it's metaphysically noncontingent, while there are arguments for the thesis that don't make the presupposition.