The present article reports third-year findings from a three-year longitudinal, experimental-control study involving 31 Spanish-speaking preschoolers (aged 38-48 months) randomly assigned to two Head Start classrooms. In Year 1 preschoolers were randomly assigned to a transitional bilingual education (TBE) or predominantly English classroom, and their receptive and expressive language and phonological awareness skills were measured in English and Spanish through two years in preschool and their kindergarten year. The TBE model was found to confer significant benefits in Spanish-language and literacy development without cost to English development. Future research directions and implications for practice are discussed. (Contains 6 tables and 4 figures.)