John Finnis is one of the seminal contemporary jurisprudential thinkers working within the natural law tradition. His Natural Law and Natural Rights, first published in 1980, has had a significant impact and stands as a centerpiece of modern natural law theory. It is at once a work of ethics, political philosophy as well as jurisprudence. The starting point of his theory of natural law con­sists in concepts such as basic human goods, practical reasonableness and the common good. These concepts provide the foundation for his analysis of communities and society as well as the legal system. This thesis sets out to expound on his theory of natural law by exploring Finnis’ understanding of the basic human goods, practical reasonableness and the common good and the way they interact with his ideas of law and justice. Some of the more controversial or contentious aspects of his theory will also be addressed; such as the supposed self-evident nature of the basic goods and their incommensurable status. Some critics allege that his theory is lacking some of the defining characteristics of a natural law theory and that it thus fails as a theory of natural law, while others have claimed that his theory lends itself to the justification of an authoritarian society. Some of these criticisms carry more strength than others and I conclude by granting that Finnis’ theory contains some weaknesses. However, these should not weaken our appreciation of his vision of the good that law can do and the interrelatedness of law and morality.