Defining an institution as a public system of rules that sets out positions, rights and duties, this book uses a philosophical argument to analyse the roles that social, economic and political institutions play in conditioning the justification, scope and content of principles of justice. It critically evaluates a number of positions about the role of institutions in generating requirements of distributive justice and considers their implications for the scope - global or otherwise - of justice. It then develops a novel theory about the role political and economic institutions play in determining the content of requirements of distributive justice and, in a cosmopolitan argument against statist positions, shows how they can affect the scope of application of these requirements.