This book presents an overview of the parameter setting theory of learnability in first (L1) and second (L2) language acquisition within the generative linguistic framework. It also attempts to challenge and refine common assumptions underlying the model. The book comprises five central chapters as well as short introductory and concluding chapters. The introductory chapter summarizes the general aim of the book and the specific aims of the chapters to follow. In chapter 2, Ayoun presents historical background on the concept of parameter throughout different versions of generative linguistics and distinguishes the standard notion of parameter from the notions of associated clusters of structures, microparameters (referring to structures), and macroparameters (which apply to a family of typologically different languages). This chapter also reviews the concept of parameter setting for language changes, creole formation, computational linguistics, and neurolinguistics, ending with a brief discussion of Universal Grammar and the Critical Period Hypothesis. In brief, this chapter argues that the parameter setting approach is a model worthy of further development and refinement, capable of explaining and predicting a wide range of phenomena in linguistic theory and its applications despite misunderstandings and lack of clarity in the field.

Chapter 3 focuses on parameter setting and resetting in L1 and L2 acquisition. Additionally, the type of triggering experience needed to set or reset a parameter and the implications of this set or reset are discussed. Here, the concepts of continuity and maturation are introduced, and Ayoun argues in favor of maturation as the correct approach for L1 acquisition. However, she appears to equate maturation with growth and emergence in general and not with the biologically timed concept originally intended by Radford (1990) or Wexler (1994). Ayoun believes that parameters begin as unset rather than set for particular values, that some parameters take longer to set than others, and that parameter resetting in L2 acquisition is possible in principle.

Chapter 4 discusses parameters of Universal Grammar and gives examples of syntactic, semantic, morphological, lexical, and phonological parameters. Ayoun then considers in detail the null subject and the verb movement parameters as they evolved throughout the theory. Chapter 5 presents the empirical research on L1 and L2 acquisition generated by these two parameters and concludes that parameters in L2 acquisition are not set instantaneously as the theory predicts but that syntactic properties associated with these parameters take time to unfold. However, Ayoun sees no reason to abandon parameter resetting as a theory to explain L2 development.

In chapter 6, Ayoun argues that parameters are not necessarily binary (i.e., having one of two possible values) but rather can be better characterized as multivalued and not mutually exclusive. Evidence for these claims comes from languages that exhibit some properties of a parameter and not others. According to Ayoun, this view of parameters better captures the empirical results of L1 and L2 acquisition presented in chapter 5.

In the last 3 years, three important textbooks on generative approaches to SLA with impressive empirical coverage have appeared: Herschensohn (2000), Hawkins (2001), and White (2003). How does Ayoun's book fit within this canon? Ayoun's book traces the history of the term parameter and the evolution of parameters within the theory. Presenting a limited sample of empirical data, she also questions traditional views of parameter and seeks ways to salvage the paradigm for further hypothesis testing and experimentation in language acquisition research. Although apparently only intended to explain L1 and L2 acquisition, the book also incorporates other areas of linguistic theory that also rely on the concept of parameters.

In general, however, the book is hard to read. Within each chapter, there are problems with organization, argumentation, clarity, and coverage. For example, definitions and examples of parameters are presented in chapter 4, when they would have been more appropriately presented in chapter 2. Similarly, in chapter 3, a section entitled “What Is a Trigger?” follows the section entitled “Is There a Triggering Problem?” In terms of argumentation, there are several contradictions. The most notable stems from Ayoun's tone throughout the book, which is sometimes too critical of parameter theory, yet wants to convey the message that the theory has much to offer. In terms of coverage, some chapters (e.g., 2 and 3) cover a variety of issues, and the focus of the discussion is lost. Finally, in terms of style, there are too many quotations from other sources that make the reading cumbersome. Still, researchers and graduate students interested in linguistic theory and language acquisition might find this book useful.