Instruction in regular letter-sound relationships is a key element of teaching children to read. However, in the English language, many words have irregular spellings (e.g. "said," "are," "yacht"). What is the best way to help children learn to read these words? To date, a number of different viewpoints have been put forward, but these viewpoints are seldom directly compared, and there is very little empirical evidence to adjudicate between them. Therefore, in this review, we outline the theoretical arguments for and against different methods of instruction, and synthesise the empirical research that does exist. We make recommendations for practice, and outline key areas where further evidence is required.