This concise book on individual differences (IDs) in SLA presents research on topics such as language aptitude, motivation, cognitive styles, student self-regulation, and personality traits. Its in-depth treatment of the field will make it valuable to researchers in applied linguistics and second language (L2) studies. At the same time, its straightforward presentation and conversational tone should make it accessible to language teachers and students of L2 pedagogy interested in understanding more about what individual learners bring to the classroom.

Dörnyei's overall goals are ambitious: to provide a single-authored, book-length summary of variables that contribute to IDs in SLA (something that has not been done since the publication of Skehan's, 1989, book, Individual Differences in Second Language Learning), to clarify theories in the field, to define measurable, theoretical constructs pertaining to IDs, and to describe seminal instruments used to assess those differences. Dörnyei also aims to “show that IDs are related to some of the core issues in applied linguistics and that they can be meaningfully linked to the most important processes underlying SLA” (p. 3).

The first chapter briefly reviews the history of how scholars in psychology and SLA have defined IDs. Dörnyei also presents his taxonomy of IDs and explains how IDs are grouped and presented in subsequent chapters to align with this taxonomy. The next five chapters describe in depth particular IDs that have received much attention in recent years: personality, temperament, and mood (chapter 2), language aptitude (chapter 3), motivation and self-motivation (chapter 4), learning styles and cognitive styles (chapter 5), and language learning strategies and student self-regulation (chapter 6). Chapter 7 briefly visits other IDs, including anxiety, creativity, willingness to communicate, self-esteem, and learner beliefs. In the brief concluding chapter, Dörnyei discusses the “situated nature of L2 learning” (Ellis, 2004, p. 546)—the observation that IDs interact with the L2 learning environment—and discusses how recent ID research necessarily implements more qualitative methods, such as interviews that complement and triangulate data from questionnaires and tests, because of this dynamic environment. He also calls for more complex theoretical paradigms to represent the complex nature of IDs, more mapping of IDs to SLA processes, and fewer oversimplified psychological models.

In this volume, Dörnyei poses difficult questions that are certain to spur some much-needed debate and discussion. For example, in chapter 4, Dörnyei describes how researchers often misinterpret Gardner's (2001) theory of L2 motivation and proposes a reconceptualization of motivation under the self-regulated learning paradigm (Zeidner, Boekaerts, & Pintrich, 2000). In chapter 6, Dörnyei asks a provocative question: Do learning strategies exist at all? He explains that distinguishing L2 learning strategies from other strategies or things that are not strategies is almost impossible, given the all-encompassing taxonomies of L2 learning strategies that exist today. He points out problems in using existing strategy questionnaires for SLA research (“the practical vs. psychometric use dilemma,” p. 184) and promotes the continuation of strategy research through the monitoring of students' self-regulation of their strategy use, which enhances their L2 learning.

Dörnyei's incisive yet comprehensive critiques of past research might cause students new to the field to wonder why past researchers chose the methods that they did. Those with more experience in the field might be troubled with what they might see as oversimplifications of prior research and rejections of long-standing conceptual operationalizations. For example, some might slightly disagree with Dörnyei's chapter 3 description of Carroll and Sapon's process for designing and validating the Modern Language Aptitude Test as atheoretical. One could counter that Carroll and Sapon's test development process (described in more detail in Carroll's 1962 publication) was informed, where possible, by the intelligence and test design theories available at the time and was part of initial L2-aptitude theory development. Dörnyei acknowledges that he has “made a number of strong claims in this book which might generate controversy and which even some of my friends whose opinion I value will disagree with” (p. 9). The discussions that result, however, will, as he predicts, engender a better understanding of the role of IDs in SLA.

Dörnyei should be heartily commended for this work, which demands debate, pushes the field forward, and enriches our understanding of IDs as they relate to processes in SLA. This volume is a valuable resource eminently suitable as a textbook for graduate students studying IDs. It is also highly recommended as a reference for those conducting research on IDs.