This research examines the hypotheses about how print represents the speech that preliterate children select when they receive input compatible with several such hypotheses. In Experiment 1, preschoolers were taught to read hat and hats and book and books. Then, in generalization tests, they were probed for what they had learned about the letter s. All of the children were able to transfer to other plurals (e.g., to decide that bikes said “bikes” rather than “bike,” and that dog said “dog” and not “dogs”), but only those who knew the sound of the letter s prior to the experiment were able to decide, for example, that bus said “bus” and not “bug.” The failure to detect the phonemic value of s on the part of alphabetically naive children was replicated in Experiments 2, 3, and 4, which instituted a variety of controls. In Experiment 5, it was found that, although preschoolers who had been taught to read pairs of words distinguished by the comparative affix er (such as small/smaller) were able to generalize to other comparatives (e.g., mean/meaner), they could not generalize to pairs where er had no morphemic value (e.g., corn/corner). A similar failure by alphabetically naive children to detect the syllabic, as compared with the morphemic, status of the superlative affix est was found in Experiment 6. Overall, the results indicate that most preliterate children fail to select phonologically based hypotheses, even when these are available in the input. Instead, they focus on morphophonology and/or semantic aspects of words' referents. The research is couched in terms of the Learnability Theory (LT) (Gold, 1967), which provides a convenient framework for considering a series of interrelated questions about the acquisition of literacy. In particular, it is argued that if the data available to the child includes the pronunciation of written words, the alphabetic principle may be unlearnable, given the hypothesis selection procedures identified in these experiments.