Since the middle 1980s, the study of the acquisition of Spanish has blossomed, becoming a diverse field in which new avenues for original research are still quite abundant. More specifically, this volume addresses examples of morphosyntactic optionality observed in the interlanguage grammars of Spanish language learners, both first language (L1) and second language (L2). Furthermore, it describes how morphology can trigger the acquisition of new syntactic knowledge. A major strength of the collection lies in the numerous and varied original contributions it makes to our knowledge of the acquisition of Spanish morphosyntax.

The book contains eight chapters: four devoted to the study of the L1 and bilingual acquisition of Spanish and four to the L2, preceded by an introduction by the editors. In chapter 1, Bel examines how two groups of children—one learning Catalan and the other learning Spanish—begin using tense. She argues that children understand tense—that is, they produce past and present tense in the appropriate contexts. Bel notes, however, that the children's VP structures are still “truncated” and “defective” compared to adult target usage. In the next chapter, Ezeizabarrena looks at the use of root infinitives (RIs) by Spanish monolingual, Basque monolingual, and Spanish–Basque bilingual children. The researcher found that all three groups produced RIs, even though both languages are pro-drop, which challenges Wexler's (1994) assumption that RIs cannot occur in pro-drop languages. A distinctive strength of this study is how the researcher teased apart RIs that occurred in inappropriate contexts from those that could be grammatical. In chapter 3, Fujino and Sano propose a null object stage in the L1 acquisition of Spanish using data from the CHILDES corpus. The authors maintain that this null object stage is a product of failing to place the correct clitic at spell-out and not related to the null object parameter. In the last chapter on L1 acquisition (chapter 4), Sánchez studies the acquisition of object clitics in Spanish monolingual children and Spanish–Quechua bilingual children. The two groups of children used Spanish object clitics similarly, except that the bilinguals produced more null objects and object topicalizations (structures permitted in Quechua and common in Andean Spanish) than their monolingual counterparts, a difference Sánchez attributes to input conditions.

In the next four chapters, adult L2 acquisition is discussed beginning with Montrul and Slabakova's treatment of aspect in Spanish in which intermediate and advanced Anglophone learners demonstrated their knowledge of the morphosyntactic and semantic qualities of the preterite and imperfect tenses. It was shown that the acquisition of these two qualities is closely tied together and that nativelike acquisition of them is possible. In chapter 6, Bruhn de Garavito and White look at how Francophone learners of Spanish acquire aspects of the determiner phrase. They found that although prenominal adjective placement was readily acquired, the learners made errors in gender agreement, perhaps, as the authors suggest, because they use one gender (usually masculine) as a default due to the idiosyncratic nature of Spanish gender. Next, in chapter 7, Pérez-Leroux, O'Rourke, Lord, and Centeno-Cortés examine whether English-speaking L2 learners of Spanish can acquire possessor-raising grammar. They argue that learners can acquire this structure, although when a subject-control predicate was present, the learners made more errors, possibly due to the input they had received. In the last chapter, Liceras, Diaz, and Salomaa-Robertson present data on the acquisition of Spanish noun-noun compounds. The authors provide evidence that L2 learners of Spanish, regardless of L1 background, do not have access to the [+word marker] feature of Spanish nouns. The authors suggest a top-down processing strategy as a possible reason for the L2 learners' divergence from the L1 target structure.

Overall, Pérez-Leroux and Liceras have given the language acquisition field a strong, varied, and useful collection of studies that contribute to our knowledge of Spanish morphosyntax. As to weaknesses, the chapter contributed by Sánchez is dense and assumes very thorough knowledge of the structures and theories addressed, which may cause some problems for less advanced readers. Also, there are certain typographical errors in the examples and tables throughout the collection that could cause confusion for some readers. Nevertheless, I would recommend this volume for a graduate-level seminar in Spanish applied linguistics, provided that the reader has sufficient knowledge of the theories and terminology employed.