Book reviews 373

Yip and Matthews ’ latest book makes a welcome new contribution to an expanding body of literature on first language acquisition in bilingual contexts. Their starting point is the presently well-established view according to which the bilingual child’s languages con-stitute separate systems. The past decade has witnessed an intense debate over whether the two linguistic systems, although separate in principle, may nevertheless interact. Yip and Matthews provide substantial empirical evidence in favour of this view, arguing that bilingual children develop differently from monolinguals. Moreover, they show that many developmental phenomena in bilingual data are paralleled by similar features in contact varieties, such as Singapore Colloquial English (SCE), and they argue that bilin-gual acquisition can have the effect of establishing substrate influence in a contact lan-guage. In particular, mutual influence occurring in bilingual development – so goes the hypothesis – provides one mechanism by which two languages in contact can converge. Chapter 1 introduces some fundamental questions, specifically: (1) How does bilin-gual development differ from acquisition of the same two languages by monolingual children? (2) Do the two languages develop independently or is there evidence fo