How do artifacts get their functions? It is typically thought that an artifact’s function depends on its maker’s intentions. This chapter argues that this common understanding is fatally flawed. Nor can artifact function be understood in terms of current uses or capacities. Instead, it proposes that we understand artifact function on the etiological model that Ruth Millikan and others have proposed for the biological realm. This model offers a robustly normative conception of function, but it does so naturalistically by employing our best scientific theories, in particular natural selection. To help make this case, it proposes “living artifacts” (organisms designed for human purposes through artificial selection) as a bridge between the artifactual and the biological realms.