This essay explores the boundaries of the moral community—the collection of agents eligible for moral responsibility—by focusing on those just inside it and those just outside it. In particular, it contrasts mild mental retardation with psychopathy, specifically among adults. For those who work with and know them, adults with mild mental retardation are thought to be obvious members of the moral community (albeit not full-fledged members). For those who work with and theorize about adult psychopaths, by contrast, they are not members of the moral community (albeit not in such a full-fledged fashion as the insane). Both psychopaths and adults with MMR have a disability, and the essay is interested in how disability sometimes exempts one from the moral community and sometimes doesn't. It will be through two associated puzzles that we will eventually come to see the complicated tripartite relation between disability, responsibility, and moral community.