A timely contribution to a field gradually coming into its own, this is the first textbook to focus on bilingual first-language (L1) acquisition. With its user-friendly presentation, this volume should be accessible to an interdisciplinary readership and could help to popularize the field. This book is of interest to SLA researchers because issues such as how two languages interact (i.e., transfer, crosslinguistic influence) and input conditions cut across the fields of both bilingual L1 acquisition and SLA (to the extent that they can be separated at all). Bilingual L1 acquisition is defined as language development in children exposed to two languages from birth and delineated categorically vis-à-vis early SLA (see Appendix A on making sure you are dealing with bilingual L1 acquisition).
The strengths of this book include detailed consideration of the sociolinguistic environments of acquisition. Variation is a recurring theme throughout, which highlights the substantial differences among bilingual children and their learning environments. Coverage of phonological and lexical development is informative. A discussion of language attrition and the risk of bilingual children losing one of their languages is also included.
The preface states that the focus will be “more on the empirical research findings about bilingual acquisition than on theoretical issues” (p. xv), which prepares the reader for the fact that numerous theoretical questions are left unexplored. To give the book a more solid grounding and link bilingual L1 acquisition to the so-called mother field of (monolingual) L1 acquisition, some discussion of theoretical issues in language acquisition, linguistic theory, or processing theory would be needed.
Another limitation is that the database consists overwhelmingly of English and Western European languages. For example, the five major projects mentioned all involve Western European language pairs such as German-French and Norwegian-English. The structural overlap between these languages is so extensive that the scope for theoretically possible crosslinguistic influence is limited (or it could be that actual crosslinguistic influence is invisible), as acknowledged later on in the book. When more diverse pairs such as Asian languages and English are considered, there is a reluctance to address interactions between the language systems being acquired, which might challenge the author’s separate development hypothesis. Nontargetlike examples such as the following are raised as a problem:
(1) Japanese produced by a child acquiring English and Japanese
kore watashi no?
“(is) this mine?”
(2) English produced by a child acquiring Cantonese and English
you get, I eat (p. 42)
Although it is acknowledged that these utterances are not adultlike (e.g., the Cantonese-English example lacks two object pronouns), whether they show crosslinguistic influence “remains to be seen” (p. 43). This question is not followed up until Appendix I, which discusses whether omissions can be evidence of crosslinguistic influence. The claim of crosslinguistic influence in such cases “crucially depends on comparisons with monolingual children” (p. 357), comparisons that are dismissed on grounds that seem methodological or ideological. However, it is not clear how else crosslinguistic influence could be established. For De Houwer, “cross-linguistic influence is in evidence if children’s unilingual sentences in Language Alpha use a structure from Language A that does not exist in the version of Language Alpha that children are hearing” (p. 288, emphasis added). This operational definition is incompatible with many studies that have argued for crosslinguistic influence on the basis of quantitative differences (e.g., Müller & Hulk, Reference Müller and Hulk2001). To return to the missing objects in example (2): Why would Cantonese-English bilinguals omit significantly more object pronouns than monolinguals (see Yip & Matthews, Reference Yip and Matthews2007) if not as a result of influence from their Cantonese grammar?
The text takes a number of strict methodological positions: “Diary-based studies typically cannot ‘catch’ enough utterances at the stage when children are producing sentences” (p. 283). However, what would be enough? Use of a structure in 75% of relevant contexts is set as the criterion for systematic crosslinguistic influence. Such a criterion appears idiosyncratic from the perspective of SLA, where correct use of the target feature in a given percentage of obligatory contexts is commonly set as a criterion for successful acquisition, but typically no such criterion is used to establish transfer.
In the realm of practical applications and advice, the book makes many useful points. For example, it deconstructs the ill-conceived advice of many speech therapists that one language should be given up at the first sign of any learning difficulties. Such contributions underline the importance of the work.
