Laws prohibiting religious vilification (or religious ‘hate speech’) are controversial and often criticised. On the one hand, it seems obviously wrong that someone should be insulted and humiliated on the basis of his or her religious commitments. But how far should the law go in putting controls on freedom of speech? Critics charge that religious vilification laws amount to an undue restriction of freedom of speech, and in fact may generate, rather than reduce, acrimonious religious debate in multicultural and multi-faith societies. This chapter suggests that the traditional common law of defamation may be adequate to guard against such harms as are caused by "religious vilification".