IANCO-WORRALL, ANITA D. Bilingualism and Cognitive Development. CHILD DEVELOPMENT, 1972, 43, 1390-1400. Limited to one definition of bilingualism, namely, dual-language acquisition, in a one-person, one-language home environment, experiments were designed to test Leopold's observations on the earlier separation of word sound from word meaning by bilingual compared to matched unilingual children. Attention to meaning or to sound of words was tested with the semantic and phonetic preference test, a two-choice test in which similarity between words could be interpreted on the basis of shared meaning or shared acoustic properties. The notion that bilingualism leads to the earlier realization of the arbitrary nature of name-object relationship was tested with the questioning technique described by Vygotsky. This called for the explanation of names, whether names can be interchanged and, when names are interchanged in play, whether the attributes of the objects change along with their names. The results support Leopold's observation on the earlier separation of sound and meaning by bilingual children.