To reach the national goal that all children in the United States will read at an appropriate level by the end of third grade, the Center for the Improvement of Early Reading Achievement (CIERA) has studied the reading growth of children in preschool and primary classes, both in and out of school. Our framework suggests that children need to develop their knowledge of language and the ability to recognize words fluently so that they can understand the books they read. CIERA's work has attempted to explicate how this development occurs and how supportive learning environments can foster it, especially for high-poverty and linguistically diverse children. This article reviews our work in early language development and literacy assessment and the development of word-recognition abilities, in the environments of preschools, primary-grade classes, and home-school connections, with the intention of understanding how these environments can more effectively provide the support needed for all children to attain success as readers and writers.