1." We should set the highest value, not on living, but on living well," Socrates exclaimed. l And with Crito we are still puzzling over what it means to" live well," though today we would be more likely to talk about the" quality of life." This phrase," the quality of life," has become unusually popular in contemporary normative debates in such diverse areas as medical ethics (for instance, euthanasia, abortion), environmental ethics (resource use and allocation), moral issues in law (punishment), and social justice (welfare rights, future generations). But it is not used univocally throughout these debates. Consequently an analysis of the concept'quality of life'would be helpful in attaining a clear understanding of the various ways it can be used in practical ethics. But mere sterile analysis is insufficient for we need to know which uses are morally acceptable and which are morally deficient. To accomplish this task the following steps will be taken: the moral philosopher's use is distinguished from the social scientist's use. Two traditional moral uses of" quality of life," the" eudaimonistic" use and the" equalitarian" use, are described and advanced as paradigmatic uses. The priority of the latter is advocated. Then two popular contemporary uses of" quality of life," the" exclusionary" use and the" protectionary" use, are briefly analyzed and shown to be morally indefensible.