What is the role of oral language in reading competence during the transition to school? Is oral language in preschool best conceptualized as vocabulary knowledge or as more comprehensive language including grammar, vocabulary, and semantics? These questions were examined longitudinally using 1,137 children from the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development. Children were followed from age 3 through 3rd grade, and the results suggest that oral language conceptualized broadly plays both a direct and an indirect role in word recognition during the transition to school and serves as a better foundation for early reading skill than does vocabulary alone. Implications of these findings are discussed in terms of both theoretical models of early reading and practical implications for policy and assessment.