Modes-of-being (Seinsarten) figure centrally in Heidegger's masterwork Being and Time. Testimony to this is Heidegger's characterisation of two of his most celebrated enquiries—the Existential analytic and the Zeug analysis—as investigations into the respective modes-of-being of the entities concerned. Yet despite the importance of this concept, commentators disagree widely about what a mode-of-being is. In this paper, I systematically outline and defend a novel and exegetically grounded interpretation of this concept. Strongly opposed to Kantian readings, such as those advocated by Taylor Carman and Cristina Lafont, I interpret a mode-of-being as a universal that defines a district (Bezirk)—that is, a natural class of entities that ought to be conceptualised in a special way. As such, every mode-of-being plays an important metaphysical and epistemic role: serving both to unify a natural class of a high degree of generality and as the interpretandum of an act yielding the basic-concepts (Grundbegriffe) pertaining to the entities therein. In explicating and arguing for this interpretation, I attribute a characteristically Aristotelian philosophical position to the early Heidegger, encompassing both metaphysical and epistemological realism and a conceptualist theory of universals.