What makes up reality, and how? What kinds of entity are fundamental to reality, and how do dependent entities depend on the fundamental ones? How does one entity metaphysically ground another? These questions are central to contemporary metaphysics. The papers in this collection, written by a new generation of metaphysicians, address these and related questions. They investigate the metaphysical concepts of grounding and fundamentality, and the relationship between the fundamental and all the other parts of reality. Together, these papers represent the cutting-edge of a central topic in contemporary metaphysics.