The purpose of this study was to evaluate a new program designed to teach young children about phonological structure. The program emphasizes recognition of phoneme identity across words. The experimental group of 64 preschoolers was trained with the program for 12 weeks, and the 62 controls were exposed to the same materials, stripped of reference to phonology. Comparison of pretraining and posttraining measures of phonemic awareness showed greater gains by the experimental group in comparison with controls. The increased levels of phonemic awareness occurred with untrained as well as trained sounds. A forced-choice word-recognition test showed that most of the children who possessed phonemic awareness and who knew relevant letter sounds could use their knowledge to decode unfamiliar printed words. The results are consistent with the claim that phonological awareness and letter knowledge in combination are necessary but not sufficient for acquisition of the alphabetic principle.