The authors begin by contrasting theories which suggest that children's phonological awareness is a result of the experience of learning to read and those that suggest that phonological awareness precedes, and is a causal determinant of, reading. The authors argue for a version of the second kind of theory and show that children are aware of speech units, called onset and rime, before they learn to read and spell. An important part of the argument is that children make analogies and inferences about these letter sequences in order to read and write new words.