Researchers often use metaphors to define abstract or complex phenomena in terms of more familiar concepts (Honeck & Temple, 1992). Fossilization (Selinker, 1972) is a trope coined to conceptualize a widely known but poorly understood characteristic of the majority of adult second language (L2) learners: failure to achieve targetlike competence despite continuous exposure to the target language, adequate motivation to learn, and sufficient opportunity for practice. Challenged by researchers who question the utility of the concept (see the overview in Long, 2003), Han's comprehensive and coherent eight-chapter book provides theoretical and empirical justification for the use of fossilization as an organizing trope (Kupferberg & Green, 1998) that encapsulates the meaning of adult SLA processes.

Chapter 1 challenges a prevailing monolithic view that equates L2 adult learners' ultimate attainment with permanent deviation from the target language. Instead, Han proposes a modular view that allows for different ultimate attainments across learners and within the interlanguage of each individual. Chapter 2 provides an overview of the concept evolution that foregrounds central pertinent questions such as whether fossilization is a process or a product and whether fossilization is local or global. Chapter 3 offers a review of internal and external factors that are conducive to fossilization. Han emphasizes that fossilization is internally determined by maturational and native language constraints that “can be modulated (aggravated or alleviated) by environmental, social, and psychological forces” (p. 43).

Chapters 4 and 5 provide a macroperspective on fossilization via a systematic examination of the critical period and transfer research. The latter discussion focuses on biocognitive constraints on L2 learning that undermine adult learners' ability to fully attain targetlike competence. Subsequently, in chapter 6, Han provides a microscopic view by reviewing a selection of pertinent empirical studies and methodological approaches. Chapter 7 relates theory to practice by looking at the connection between L2 instruction and fossilization. The chapter emphasizes the positive and negative influences of classroom input, pedagogic strategies, and opportunity for practice on the process of fossilization.

The final chapter summarizes the ideas presented in the book and foregrounds implications for research and practice. Han laments the lack of longitudinal studies that might establish conclusively the existence or nonexistence of fossilization. She also emphasizes that practitioners attempting to formulate realistic instructional goals should bear in mind two claims established in the book. First, fossilization is an inevitable process in adult SLA due to biocognitive constraints. Second, there are no fossilized learners because success and failure exist in each L2 learner.

The book offers a theoretical and empirical fossilization-oriented state-of-the-art review of the SLA domain. Therefore, it is a must for researchers and students interested in L2 acquisition and instruction. Han's dynamic and lucid style, well-chosen definitions, and erudite list of references and citations are commendable. Availing herself of her remarkable knowledge, Han deconstructs the meaning of central issues in the domain (e.g., ultimate attainment, factors affecting L2 acquisition, learner variables, the critical period effects, L1 transfer, and L2 instruction) in order to reconstruct her point of view systematically and coherently. At certain discursive junctions, she provides enlightening and reader-friendly summaries that are accompanied by new questions—traffic signals indicating in which direction Han intends to further pursue her goals.

Han's theory-driven arguments, the empirical evidence she surveys, and the terminology she uses (e.g., see Han's succinct definition of future research goals on p. 175) show that she has probably adopted a quantitative postpositivistic paradigm of inquiry (Lincoln & Guba, 2000). Future research could also employ qualitative data-driven approaches, such as conversation analysis, to illuminate interactive SLA processes in institutional as well as everyday settings. Such local inquiries might illuminate the coconstruction of participants' points of view and accordingly promote the understanding of the meaning of fossilization.