Aristotle takes up the topic of change (or coming-to-be and ceasing-to-be) in both the Physics and De Generatione et Corruptione. He distinguishes between simple coming-to-be (substantial change), as when something comes into existence, and qualified coming-to-be (accidental change), as when an already existing thing alters, or moves, or changes in some other way. But he also maintains a persistence principle: that in every change, whether simple or qualified, there is something that persists throughout the change. I examine the question of (...) whether this principle threatens the viability of the distinction between substantial and accidental change by comparing what Aristotle has to say about it in the Physics with what he says in GC. In the process, I discuss several recent treatments of the topic as well as some conflicting views about the role, if any, of prime matter in Aristotle's account of substantial change. (shrink)