Why should states matter and how do relations between fellow-citizens affect what is owed to distant strangers? How, if at all, can demanding egalitarian principles inform political action in the real world? This book proposes a novel solution through the concept of avant-garde political agency. Lea Ypi grounds egalitarian principles on claims arising from conflicts over the distribution of global positional goods, and illustrates the role of avant-garde agents in shaping these conflicts and promoting democratic political transformations in response to them. Against statists, she defends the global scope of equality, and derives remedial cosmopolitan principles from global responsibilities to relieve absolute deprivation. Against cosmopolitans, she shows that associative political relations play an essential role and that blanket condemnation of the state is unnecessary and ill-directed. Advocating an approach to global justice whereby domestic avant-garde agents intervene politically so as to constrain and motivate fellow-citizens to support cosmopolitan transformations, Global Justice and Avant-Garde Political Agency offers a fresh and nuanced example of political theory in an activist mode. Setting the contemporary debate on global justice in the context of recent methodological disputes on the relationship between ideal and nonideal theorizing, Ypi's dialectical account illustrates how principles and agency can genuinely interact.