Traditionally, children’s and adults’ understanding of alphabetic relationships has been conceptualised in terms of phonemes. Consequently, it has been thought that the skill that beginning readers need to learn, and the skill that experienced readers have presumably developed, is understanding the correspondences between phonemes in speech and the letters used to represent them. The phoneme has acquired its central position because the English alphabet is based on the phoneme. Thus, it is not necessarily the phonological unit that is best suited for representing speech in writing. Furthermore, phoneme-letter relationships are somewhat different in other writing systems, and thus there is no optimal relationship between spoken and written language. Surprisingly, how children begin thinking about writing in terms of phonemes, or whether skilled readers continue to do so after they have become proﬁcient in reading and spelling, has not been investigated in detail. It appears that children only gradually learn to understand the principles through which speech is represented in writing and that adults do not necessarily use phonemes in tasks that demand them to do so. In this chapter I discuss how the structure of different writing systems may affect
literacy development, and what is known about the process through which children begin tomake connections between sound units in speech and letters. Present knowledge about adults’ understanding of letter-sound relationships is also considered. I then discuss two experiments that look at children’s developing understanding of lettersound relationships as well as reviewing work by Lehtonen and Treiman (2007) that investigated adults’ use of different units in conceptualising the relationship between sounds and letters. Finally, I discuss the ﬁndings in the light of children’s and adults’ conceptions of the relationship between spoken language and print.