The editors have brought together an exceptional collection of essays examining the role of implicit (i.e., unconscious) and explicit (i.e., conscious) knowledge in SLA from a theoretical (Part 1) and empirical (Parts 2, 3, and 4) perspective. The volume includes the finest presentations at the 2009 Georgetown University Round Table on Languages and Linguistics and covers controversial issues about implicit-explicit learning and SLA in general: Is language learning nature or nurture driven? What is the nature of second language (L2) knowledge? Are implicit and explicit learning separate mechanisms or do they interact? What makes some L2 processes dependent on attention, awareness, or neither of the two? What can and cannot be learned explicitly? What internal and external factors affect adult SLA? Can bilingualism compensate for age-related limitations?

Part 1 constitutes the theoretical pillars of the volume and includes four chapters. In the first chapter, VanPatten claims that syntactic acquisition follows fixed developmental stages, which are resistant to explicit instruction because syntax is learned implicitly through input and innate language mechanisms (i.e., Universal Grammar). This nativist approach contrasts with the usage-based approaches described in the following chapters. On the one hand, Reber believes in an unconscious general learning mechanism tuned to pragmatic and social functions, which conceives communication as the ultimate goal of language acquisition. On the other hand, Ellis advocates for a model grounded in the notions that implicit and explicit knowledge interact, and that adult SLA requires conscious and explicit learning to overcome the processing biases that result from years of exposure to first language habits. Focusing on the consequences of a lifelong experience speaking multiple languages, Bialystok posits that L2 development depends on the interaction of analysis (domain specific) and control (domain general) and shows that bilinguals have weaker linguistic representations for each language but stronger attentional control and executive skills than monolinguals. The four chapters constitute a shrewd, solid piece of work that makes the volume a streamlined reference on the topic of implicit and explicit learning.

The rest of the book includes a potpourri of empirical studies that explore an array of L2 issues that vary in their relevance and significance to the topic of implicit-explicit learning. The studies focusing on cognitive factors reveal that awareness is a complex construct (Leow, Johnson, & Zárate-Sández), that working memory can predict L2 learning over a semester (Linck & Weiss), and that acquisition patterns for the perception and production of a phonological contrast do not coincide (Eckman, Iverson, Fox, Jacewicz, & Lee). The studies exploring a combination of learner-based (e.g., age, gender, L2 proficiency) and externally induced (e.g., feedback type, learning context) factors affecting SLA indicate that implicit feedback is more effective than explicit metalinguistic feedback for older—but not for younger—adults (Lenet, Sanz, Lado, Howard, & Howard), that immediate and delayed feedback are equally effective (Henshaw), and that studying at home produces similar—but more delayed—benefits on oral accuracy and written competence than studying abroad (Pérez-Vidal, Juan-Garau, & Mora). With respect to L2 proficiency effects, beginners have no advantage over advanced learners in perceiving certain L2 vowels (Gordon), but they differ in their reliance on explicit knowledge (Hilton), content words, and sentence-initial information (Rast); female and less proficient learners use fewer compensation and metacognitive strategies than male and more proficient ones (Lin). Finally, the studies investigating the consequences of bilingualism show that bilingual twins do not maintain a common phonological system for both languages due to their shared genes and environment (Ingram, Dubasik, Liceras, & Fernández Fuertes) and that older bilinguals are more accurate and faster in inhibitory control tests than monolinguals, suggesting that bilingualism can counteract age-based deficits (Finger, Billig, & Scholl).

This volume represents various theoretical postures on how languages are learned and what place instruction plays in different areas of language acquisition. The versatile and compelling nature of the book will capture the interest of a broad audience. Researchers and graduate students will find this book a treasured resource on implicit and explicit learning. Language practitioners in search of a practical guide to make classes more effective will enjoy reading about the most recent findings from empirical studies presented in an accessible and engaging manner. All audiences will benefit from the extensive use of examples and concrete studies to illustrate the models’ arguments. Finally, a volume that straddles the domains of psycholinguistics and L2 pedagogy to investigate implicit and explicit learning in SLA could not be better timed or more welcome, considering the fact that cognitive accounts of SLA are gaining ground, and more L2 researchers are turning to psychology in search of theories and assessment techniques to better understand how people process foreign languages.