While the phrase "metaphysics of science" has been used from time to time, it has only recently begun to denote a specific research area in which metaphysics meets philosophy of science-and the sciences themselves. The essays in this volume demonstrate that metaphysics of science is an innovative field of research in its own right. The principle areas covered are: modal metaphysics of properties, realism in mathematics and its relation to science, dispositions and their relation to causation, pandispositionalism, and natural kinds.