Proficient reading is one of the most important intellectual tasks a child will accomplish in his or her lifetime. It is an ability that depends upon a number of component skills and takes several years to master fully. This chapter outlines research concerned with the cognitive skills that have been investigated in relation to normal reading development. Gough et al. (1992) point out that there are only 26 letters in the English alphabet but more than three dozen phonemes and that “the process of reading acquisition is aptly and accurately described as a process of cryptanalysis or codebreaking” (p. 39).