Adam Smith’s theory of money played a key role in his development of one of the conclusions for which he is most famous today: the superiority of the system of natural liberty to mercantilism. This essay examines the part played by money in this argument, and specifically Smith’s theory of money’s origins and evolution and its relevance to his theory of natural liberty. The essay goes on to show how his position contributes to his critique of mercantilism and other proto-monetary policies as illustrative of his wider objection to interventionism, in conjunction with his understanding of the ‘science of the legislator’ in promoting the realisation of the system of natural liberty.