The claim that metaphysics is fundamental has frequently been voiced in the history of the discipline. However, the usual ways in which this claim is justified do not appear to be effective. This article aims to fill this gap in meta-metaphysical theory by providing a credible justification of the fundamentality of metaphysics in two steps. The first consists in establishing a set of five conditions of fundamentality for the discipline. The second consists in showing that these conditions are satisfied when (...) the object of study of metaphysics is identified with an ontologically neutral object, namely categories, and the task of the discipline is taken to be the determination of the number and identity of the most general categories and the relation of less general categories to the most general ones. (shrink)