Traditionally, children's books are in a printed format and shared book reading is done with an adult. In recent years, interactive E-books have become a common medium for children's books and shared book reading is diminishing. This study compared the contribution of book format to the development of literacy in kindergarten children. We constructed an E-book, which included a story and related activities that support literacy development. The E-book was then converted to a printed format. Both formats had identical content, such as embedded graphics and literacy activities, but there were some variations due to media characteristics.Fifty kindergarten children (5 to 6.5 years) were pair assigned to E-book reading (experimental) or printed book reading (control) condition. These pairs were matched on gender and verbal intelligence (PPVT), and they all had some experience with computers. During the first two intervention sessions children were exposed to the story, and in the next three sessions they practiced literacy activities. The E-book group listened to the story and did the activities in a digital format. The printed book group heard the same story from the experimenter, and did the same literacy activities but these were administered by the experimenter. The experimenter was instructed to be passive and just respond to children requests. The participants were tested before the intervention, after they were exposed to the story, and after the literacy practice on a battery of literacy tests: plot understanding, knowledge about print, vocabulary knowledge, phonological awareness, and orthographic awareness. Their level of involvement in the various activities was evaluated at the end of each session.Prior to the intervention, there was no statistically significant difference between the E-book and printed groups on the literacy measures. Following the intervention, the performance of both groups improved on all of the literacy measures. However, performance of the printed book group improved significantly more than the E-book group on knowledge about concepts of print, understanding of the plot, and vocabulary knowledge. The duration of the intervention session was significantly longer for the E-book compared to the print condition and there was no difference among the groups in their level of inMaterial published as part of this publication, either on-line or in print, is copyrighted by the Informing Science Institute. Permission to make digital or paper copy of part or all of these works for personal or classroom use is granted without fee provided that the copies are not made or distributed for profit or commercial advantage AND that copies 1) bear this notice in full and 2) give the full citation on the first page. It is permissible to abstract these works so long as credit is given. To copy in all other cases or to republish or to post on a server or to redistribute to lists requires specific permission and payment of a fee. Contact Publisher@InformingScience.org to request redistribution perm...