Because of the variation in support for literacy development in different homes, many children need high-quality preschool and school environments and excellent primary instruction to be sure of reading success. This Spanish-language Digest discusses the research on preschool literacy environments and their contributions to reading skills development. The overall quality of a child care program has been found to be an important determinant of positive effects on language and preliteracy skills. Studies that have focused on the language environments in preschool classrooms suggest that the quality of adult-child discourse is important, as is the amount of such interaction. Modest enhancements of the quality of classroom experiences show positive effects on children's language development and preliteracy skills. Given the pervasive evidence of differences in language and emergent literacy skills associated with class, culture, and linguistic background, it is heartening that preschool has been shown to benefit children's performance in school. (Contains 23 references.) (LPP)