The Philosophical search for Natural Kinds is motivated by the hope of finding ontological categories that are independent of our interests. Other requirements, of varying importance, are commonly made of kinds that claim to be natural. But no such categories are to be found. Virtually any kind can be termed 'natural' relative to some set of interests and epistemic priorities. Science determines those priorities at any particular stage of its progress, and what kinds are most 'natural' in that sense is always a real and lively scientific question. The general philosophical problem of scientific realism is also real; but between the scientific and the metaphysical, the Problem of Natural Kinds' sits otiose.