Preschoolers' behavior was examined over repeated sessions when interacting with one of two types of alphabet books -- traditional alphabet books in paper format or interactive alphabet books in an eBook format -- to determine the extent to which each type of book elicited behavior relating to alphabet knowledge. Data are reported from 63 3 and 4-year-old children who were assessed on letter knowledge and phonemic awareness. They were randomly assigned to conditions in which they used either paper books representing a variety of text and illustration styles, or eBooks representing a variety of audio and interactive features. Orientation to the books and letter-related behaviors in independent reading were coded in 16 sessions occurring over 8 weeks, and summarized across 2-week blocks. Children in the eBook condition spent more time oriented to the books. However, they generally engaged in less letter-related behavior (saying letter names, saying object names). In half of the observations they activated object hotspots. Moreover, their overall letter-related behavior declined over sessions. Implications for parents, educators and publishers are discussed. (author abstract)