Deuchar & Quay's Bilingual acquisition addresses theoretical issues both of language acquisition in general and of specifically bilingual acquisition through an examination of a case study involving one child's acquisition of English and Spanish in England. Regarding the first issue, the authors attempt to answer questions of phonological differentiation based on acoustic evidence, lexical differentiation in relation to the idea that children avoid lexical synonymy in early stages of language acquisition, and lexical categorization of two-word utterances and the emergence of language choices. Regarding the second issue, they are concerned with the question of whether children possess one or two language systems, and they explore the criteria involved in making such a distinction. Finally, they investigate the factors of the language situation that influence a child's language choice.