The positive effects of shared book reading on vocabulary and reading development are well attested (e.g., Bus, van Ijzendoorn, & Pellegrini, 1995). However, the role of shared book reading in GRAMMATICAL DEVELOPMENT remains unclear. In this study, we conducted a construction-based analysis of caregivers' child-directed speech during shared book reading and toy play and compared the grammatical profile of the child-directed speech generated during the two activities. The findings indicate that (a) the child-directed speech generated by shared book reading contains significantly more grammatically rich constructions than child-directed speech generated by toy play, and (b) the grammatical profile of the book itself affects the grammatical profile of the child-directed speech generated by shared book reading.