It is well-established that participation in shared book reading interactions with caregivers supports children's early language and literacy development. Most of this literature focuses on reading experiences during the preschool period. Less is known about the nature and importance of such practices during infancy. Therefore, the goal of this study was to examine literacy practices between parents and infants in a large cohort study, Growing Up in Ireland. Interview, survey, and direct measurements of children's language skills were used to examine whether parent-report of book reading practices when children were 9-months predicted child expressive vocabulary at 36-months (N = 9171). Regression analysis indicated that approximately 80% of 9-month-old Irish children are read to by parents. Characteristics of families who were more likely to report reading with children emerged: those with higher educational attainment, fewer depressive symptoms, and those who report a high-quality home language environment (e.g., reported talking more to children during everyday activities). Furthermore, children who were read to at 9-months had stronger expressive vocabulary skills at 36-months, even after accounting for socio-demographic and home literacy environment covariates measured at both 9- and 36-months. Results are discussed using a bioecological framework to describe how proximal and distal factors in the child's environment converge to impact early childhood literacy development.