This chapter argues that a strong case can be made on contractarian grounds that persons of diverse citizenship have distributive obligations to one another analogous to those of citizens of the same state. Obligations or justice might be thought to be more demanding than this, to require greater sacrifices on the part of the relatively well-off, and perhaps sacrifices of a different kind as well. If social cooperation is the foundation of distributive justice, then one might think that international economic interdependence lends support to a principle of global distributive justice similar to that which applies within domestic society. The main features of contemporary international interdependence relevant to questions of justice are the results of the growth of international investment and trade. In an interdependent world, confining principles of social justice to domestic societies has the effect of taxing poor nations so that others may benefit from living in "just" regimes.