In order to articulate a political philosophy that applies beyond state action, John Rawls took the "the basic structure of society" as the first subject of justice. In this dissertation, I explain both what the basic structure of society is and why it is an appropriate subject in moral theory. As the set of institutions that specify our valid claims as members of society, the basic structure has a profound influence on the content of ethical life; shaping our values, virtues, relationships, and obligations. In order to adequately assess this influential set of institutions, we should treat the the basic structure as a fundamental moral concern.