In this paper, I defend a version of the medical model of disability, which defines disability as an enduring biological dysfunction that causes its bearer a significant degree of impairment. We should accept the medical model, I argue, because it succeeds in capturing our judgments about what conditions do and do not qualify as disabilities, because it offers a compelling explanation for what makes a condition count as a disability, and because it justifies why the federal government should spend hundreds (...) of billions of dollars, annually, on aid and accommodations for disabled people. After responding to a pair of objections Elizabeth Barnes has raised against the medical model, I contrast it with Guy Kahane and Julian Savulescu's welfarist account of disability, and with Barnes's own mere-difference view. Both of these accounts face serious challenges, although elements of Barnes's view can—and, in my opinion, should—be adopted by proponents of the medical model. (shrink)