Child SLA study is undoubtedly less researched than bilingualism and adult SLA, and this volume is welcomed for its contribution to our understanding of younger language learners. There is a distinct bias in this volume toward a focus on discourse and the social contexts of learning; however, it is unclear why the subtitle should be “Child’s Play,” because there is only minor attention to play as a learning environment and no overt consideration of the implication of this phrase that language acquisition is easy for younger learners.

Qualitative glimpses into the learning contexts are provided by Fogle’s chapter, which compares the facilitative conversations between a father and his two adopted Russian children with those that occur in another adoptive family with a more sink-or-swim attitude. Mitchell and Lee’s presentation of home language and literacy events engaged in by three Korean children learning English with support from their second language (L2) English-speaking mother and a first language (L1) English peer also shows the moment-by-moment characteristics of the child’s SLA environment.

In contexts of more overt instruction, the picture is different and sometimes more worrisome. Philp and Duchesne explore the language demanded of, and used by, an Ethiopian 6-year-old in a classroom of Australian peers with whom she must negotiate her roles and relationships. Cekaite explores a similar environment but with a focus on the pedagogical function of attempting to initiate exchanges with the teacher. Oliver, Philp, and Mackey address the impact of teacher guidance in task-based interaction on learners of different ages. Van den Branden contributes the concerning picture of multiple missed opportunities for learning in a Flemish classroom in which children remained silent when they did not understand.

The chapter by Iwasaki purports to be a naturalistic study of a 7-year-old’s Japanese verbal morphosyntax acquisition. However, the heavy focus-on-form environment of the classroom, in which much of the Japanese exposure occurs, suggests that it may be a combination of natural and instructed acquisition. On the other hand, Kwon and Han’s exploration of transfer in the acquisition of negative, plural, and possessive structures in a 3-year-old Korean learner of English is clearly naturalistic and exposes the multidirectionality of transfer. Reference to the transfer literature in early bilingualism research would have made this study even stronger.

Dimroth’s study of the acquisition of untutored German by two Russian learners, 8 and 14 years of age, puts the emphasis on the differences between younger and older child learners and argues for a multifaceted approach that includes neurobiology, motivation, cognitive development, and prior linguistic knowledge and experience as sources of explanation. The differences between younger and older learners is also clear in the studies of adolescent learners in classrooms who seem able to profit both from incidental focus-on-form—at least in the short term, as shown by García Mayo and Alcón Soler’s study of Spanish learners of English—and from explicit instruction—as shown by White’s study of French and Catalan learners of English.

Both Philp, Mackey, and Oliver in the introduction and Nicholas and Lightbown in their chapter argue for child SLA as a distinct phase of language learning. Nicholas and Lightbown argue that it extends from age 2, when they claim children have understood Language with a capital L, to about age 7, which they argue is a watershed of acquired skills and understanding of the particular languages being learned. However, it is not clear what understanding Language means for these authors, and in the end it seems they say little more than that child SLA is defined by being a child and by having already started learning a L1. In fact, it seems inappropriate to try to argue for discrete periods of language learning, given the myriad linguistic and nonlinguistic developments taking place at the same time. Instead, a better understanding of the specific constellations of knowledge, capacities, and needs of children across childhood and adolescence and how these constellations shift and change over time is needed. Only in that way will the insights from language acquisition at all ages, in all contexts, and with all abilities be brought fruitfully together.