Harvard Graduate School of Education will investigate the use and effects of information book read alouds, in comparison to storybook read alouds, in Head Start classrooms. Specifically, the study seeks to answer three research questions: (a) What is the availability and use of information books, in comparison to storybooks and books of other genres, in Head Start preschool libraries and Head Start teacher read alouds? (b) Do information book and storybook read alouds have the same effect on preschool children's learning of vocabulary introduced in the books or does the effect differ by genre? (c) Do children who participate in information book and storybook read alouds differentiate their pretend reading by genre? Study participants will include the teachers and students in thirty Head Start preschool classrooms. Children will participate in read alouds, and a sub-sample of children will be randomly selected to participate in vocabulary assessments and pretend readings of books in each genre. Results of the study are expected to support the appropriateness and importance of reading aloud to young children in the information book genre, as well as the more commonly studied storybook genre.