Abstract: This dissertation examines Aristotle’s inquiry on void in his Physics, Book IV, chapters 6-9. There, Aristotle presents numerous arguments against the existence of void. He finds that void is not only unnecessary for physical phenomena but impossible. Before doing so, he seeks an answer to what void is, if it exists, finding that if void exists, it is place deprived of body. He then proceeds to target that thing in his subsequent refutations. I begin the dissertation by asking the prior, methodological questions, how can Aristotle by his own lights think that there is a correct answer to what a nonexistent item is? And how could Aristotle target that thing in a demonstration of nonexistence, given this that logic precludes the use of empty terms, i.e., terms which fail to signify an existent, and ‘void’ would be such an empty term? I find that Aristotle has a considered method for approaching nonexistence inquiries, which is a counterpart of his method for existence inquiries in Posterior Analytics II 1-2. It emerges within the context of this counterpart method that Aristotle has certain grounds for saying what a nonexistent thing like void is, if it exists, and so too, that Aristotle can prove by demonstration the nonexistence of something using his own logic without violating the existence entailments of that logic. I then turn to examine Aristotle’s answer to what void is, if it exists: place deprived of body. I find that Aristotle targets a consistent account of void throughout the inquiry, though according to this account there will be both a separated void and inseparable voids. I next consider Aristotle’s lengthy engagement with his predecessors, which, I find, tells us much about the intellectual and historical context around void. I argue against the scholarly orthodoxy and maintain that, in fact, the atomists likely never argued for the existence of void. Finally, I turn to Aristotle’s most complex argument against the existence of void, the so-called ‘cube argument’ at 216a26–b20. I offer a straightforward reconstruction, which resolves interpretative difficulties and reveals a compelling attack on void.