The development of bilingual skills in the early years is a complex process, where the outcomes are dependent on a dizzying array of factors. In her recent book, Silva-Corvalán provides a most rigorous treatment of the subject, using as her focal point her two grandsons who were acquiring Spanish and English in a Los Angeles suburb. Their mother was an English speaker with whom the children spoke English (although she learned some Spanish), their father a Spanish speaker with whom the children initially spoke in Spanish, and the author of the book a Spanish speaker with whom the children were to speak in Spanish.

In this ever more multilingual world, there are advantages to being multilingual and increasing opportunities for children to be raised bilingually and even trilingually, with each parent speaking a different language to their children, and the grandparents yet a third. Books, in fact, have appeared that tutor parents on how to raise their children trilingually (e.g., Wang, Reference Wang2008). Whereas the author of the current book cites a series of comprehensive case studies of bilingual first language acquisition (p. 3), she notes that none of these studies looked in depth at the Spanish-English bilingual development of two siblings from their first word to age 6, as this book does. So although this book is not groundbreaking in its focus on the development of multilingual skills in young children, it is most certainly innovative in terms of the rigor with which it treats the linguistic development in two young boys for whom English is the dominant language, with Spanish input limited to perhaps one third of the time.

Being a native speaker of Spanish—the endangered language of these two Spanish language heritage learners—the author had a Ph.D. in linguistics and was a professor in Spanish linguistics at a nearby university. So the preconditions for the study were in place. What makes this study and the book so impressive is the incredible thoroughness with which Silva-Corvalán embraced the task at hand—describing fully and minutely the ins and outs of language development in her two grandsons from the onset of language to the age of 6. Through the use of diary entries and audio recordings she steadfastly recorded their language in both English and Spanish as it developed. She tracked, for example, the mean length of utterance in spontaneous speech over a 5-year period for each child. She charted the development from one to two words and beyond. Among other things, she looked at their question-asking behavior, their use of prepositions, and their use of the possessive. In addition, she described their metalinguistic awareness as it developed and noted their mixing and switching of languages as their discourse developed.

Of great value to other researchers, she meticulously analyzed their language forms, relating their development to other research in the literature and comparing their performance to that of adult heritage speakers. She also solidly grounds her findings in the literature on English and Spanish language development in both children and adults. She has separate chapters on the acquisition of ser, estar, and be. Additionally, she has a chapter on the development of verb morphology—learning how to deal with tense, aspect, and mood, which are three areas that pose challenges for learners, especially in a second language.

Silva-Corvalán arrives at the conclusion that bilingual acquisition is achieved through the convergence of numerous factors: the structure of the contact languages, the linguistic and cognitive complexity of the language to which the children are exposed and the nature of the exposure, the quality and quantity of the input, the children’s language dominance, their proficiency in the languages, and their language use patterns. The author provides a truly comprehensive description of how the two youngsters fair in their bilingual language development. Although probably too technical for the average parent, this description should prove extremely valuable to researchers in the field.