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.