This article proposes that educational personalization may be usefully understood from a process perspective. It defines educational personalization as that which occurs within any "planning or decision-making process" which runs for one student at a time, and uses "information from or about individual students," in order to output educational plans and decisions for them. Importantly, understanding personalization as a process illuminates what it is that we design when we design for personalized education (that is, planning and decision-making processes) -- and helpfully suggests familiar process-analytic vocabulary (e.g. 'trigger', 'agent', 'rules') for describing the further designable elements of those processes. It is argued that this simple, inclusive definition forms a consensus point from which to conduct research and design conversations about personalized education. In particular, it allows for the orderly comparison of diverse designs, toward increasing our knowledge of what makes for 'good' personalization.