This article overviews the research on the complex relationship betweenbilingualism and cognitive development and the important implications ofthis relationship for bilingual education. Recent studies are discussed thatexamine the cognitive development in bilingual children with regard tometalinguistic awareness, concept formation, and analogical reasoning. Acase is made for additive bilingual instruction in early childhood programs asa means of reinforcing the productive and receptive knowledge of the firstlanguage during this critical period of linguistic, social, and cognitivedevelopment.