Many authors have proposed that grounding is closely related to metaphysical laws. However, we argue that no existing theory of metaphysical laws is sufficiently general. In this paper we develop a general theory of grounding laws, proposing that they are generative relations between pluralities of propositions and propositions. We develop the account in an essentialist language; this allows us to state precisely the sense in which grounding might be reduced to laws. We then put the theory to use in showing (...) how moral laws can play a role in grounding particular moral facts, in defending monism about ground, and in showing in what sense there is no gap between the grounds and the grounded. Finally, we make a novel proposal about what grounds facts about ground. (shrink)