The Law of Peoples, it is claimed by John Rawls, is deeply influenced by Kant’s Perpetual Peace, and in many respects one can easily identify the continuities between the two texts. In particular Rawls holds to the possibility – ever present in Perpetual Peace – of progress towards a worldwide, peaceful federation. This paper will focus upon the extent to which there are consistencies between the two philosophers with respect to the underlying ideas that provide grounds for this belief in progress. In particular, Rawls’ account of moral learning and the possibilty that peoples (i.e. collectivities) are capable of such incremental improvements will be examined, and the philosophical assumptions that are central to these claims. This analysis will require further, more detailed examination of Rawls’ assumptions – or omissions – with respect to the role of history and human nature, which can be compared to Kant’s philosophy from a critical, potentially fruitful perspective.