Many hold an Aristotelian metaphysic of objects: fundamentally, objects fall under sortals and have persistence conditions befitting their sort. Though sometimes offered as a theory of material objects, I argue this view is in fact incompatible with physicalism. Call a "sortal' a kind of object, a "sortal identity' a particular's nature specified in sortal terms, and "sortal properties' properties that are determined by an object's sortal identity, such as its persistence conditions. From here the argument runs as follows. Something is physical only if it is physically fundamental or is determined by what is physically fundamental (P1), but sortal identities and properties are neither physically fundamental (P2) nor determined by the physically fundamental (P3). I defend each premise in turn. P1 falls out of the standard conception of physicalism. Rejecting P2 is tantamount to positing Aristotelian substantial forms and formal causes—which are themselves incompatible with physicalism. I defend P3 by showing that extant solutions to "the grounding problem"—the problem of showing how (nonfundamental) sortal properties are determined by (nonsortal) physical properties—are either physicalistically unacceptable, or else physicalistically acceptable but opposed to the sortalist metaphysic.