Questions about reality's metaphysical structure - and thus what grounds what - are ubiquitous across philosophy. The essays in The Epistemology of Grounding offer insight into how we can answer such questions by investigating how we can know what grounds what, and how to discover metaphysical explanations. Written by a team of expert contributors, the essays include new work on conceptualism and the logic of grounding, abduction and inference to the best explanation, grounding in the sciences, knowledge of grounding on the basis of essence and identity, and an account of perceptual knowledge of grounding. Together, these contributions address an urgent need in the literature and will interest a broad philosophical audience interested in grounding and its epistemology, as well as in metaphysics and its methodology more generally.