This chapter examines the argument of Aristotle's Politics in relation to the theory of justice that he articulates in his Nicomachean Ethics. It first provides a biography of Aristotle before discussing his view of human nature, the starting point for understanding his views on both ethics and politics. In particular, it considers what Aristotle means when he describes man as a ‘social and political animal’ (zoon politikon). It goes on to explore the theory of justice developed in Aristotle's Ethics, focusing on the notions of proportional and arithmetical equality. It also analyses the two areas of social life in which the concept of justice has a practical application: the spheres of rectificatory and distributive justice. The chapter concludes with an assessment of the continuing relevance of Aristotle for political philosophy today, especially for the debate between John Rawls and his communitarian critics.