Equality is a puzzling value, both revered and scorned. Across society, some people end up worse off and others better off. Some say that there is nothing in itself morally bad or wrong with individuals being unequal in life prospects and outcomes. And some will argue that insistence on equality of condition would be incompatible with respect for the individual responsibility each person has to shape her own life and accept whatever comes. Others claim that justice is equality. In this collection of essays, Richard J. Arneson explores two approaches to these issues.One is a version of luck egalitarianism, according to which, all else being equal, there is greater moral reason to undo inequalities of condition the more those who are worse off are so through no fault or choice of their own. Luck egalitarianism aims to balance individual responsibility and equality concerns. Arneson defends equal opportunity for welfare as the best interpretation of this approach, but ultimately finds it unacceptable, on the grounds that providing opportunities is not what justice truly requires—what if providing opportunities never actually improved anyone's quality of life? A more promising approach says that justice requires giving priority to facilitating better lives for those who would otherwise be badly off—and we should add, to the morally more deserving as well. Arneson further argues that priority is a cosmopolitan doctrine with global scope, setting a demanding agenda for change. Priority combines the utilitarian liberalism of J. S. Mill and the uncompromising egalitarianism of Karl Marx.