We investigated the effect of repeated readings of an electronic book (e-book) on pre-kindergarten and kindergarten children from low (n = 127) and middle (n = 120) SES groups. Children were randomly assigned to one of three options: reading an e-book in five sessions, reading an e-book in three sessions, or receiving the regular kindergarten program (control). Pre- and post-intervention measures included vocabulary, phonological awareness, and word reading. No differences were found in the progress of children from the two SES groups. Pre-kindergarten children progressed more in phonological awareness than kindergarten children. Children who used the software five times exhibited greater progress in word reading than children who read it three times, and those who read it three times outperformed the control group. Three readings improved the children's vocabulary compared to the control but no advantage was found for five readings. Interactions appeared between age group and SES. Implications for future research and education are discussed. (Contains 2 figures and 2 tables.)