 We will proceed as follows. We will first characterize the human beings who are the subject of the debate on moral status—those with what we will call “radical cognitive disabilities.” After discussing the ways in which humans are classified as cognitively disabled, we will describe the narrower category of humans whom the debate concerns. To be clear, this is a group of humans stipulated to exist rather than classified by empirical procedures. We will note the difficulty of separating claims about such stipulated individuals from claims that some actual individuals satisfy that stipulation. Next, we will characterize the concept of moral status, describing its structure and function. We will then outline the principal differences in how that concept is understood, particularly its “inclusion criteria”—the criteria for ascribing what we will call “full moral status,” the status attributed to cognitively nondisabled adult human beings. (In calling that moral status “full,” we do not intend to take sides in the debates over whether there can be any higher moral status.) We will identify one family of moral-status accounts—those basing possession on individual attributes—as the primary, though not the exclusive, source of the challenge addressed in this entry: the claim that some human beings lack full moral status. After outlining those accounts, we will review several ways of meeting the challenge: 1) basing full moral status on individual attributes shared by a greater proportion of human beings; 2) adopting secondary grounds for the possession of full moral status—by “courtesy” or by “proxy”; 3) rejecting individual attribute accounts in favor of accounts that base the full moral status of all human beings on their species membership or their humanity. 