As a multilingual speaker, a second language educator and a researcher, I have always been fascinated by the notion of fossilization (Selinker, 1972), that is, cessation of learning in spite of rich exposure to input, adequate motivation to learn, and abundant opportunity for communicative practice. Yet it was not until after I became a student of Larry Selinker at the University of London that I began research in this area. The longitudinal study (Han, 1998) I performed then not only convinced me of the reality of fossilization, but kindled in me an even greater interest in seeking an understanding of its etiology. Why is it that learners suffer fossilization differentially? Why do L2 learners wind up with differential success in learning the L2 under seemingly identical learning conditions? What does the existing constellation of explanations tell us about lack of learning, and about the general understanding of adult second language acquisition (SLA)? Can instruction salvage learners from fossilization? These are some of the issues that have appealed to my attention and that I have tried to address in this book.

With no pretense of offering an exhaustive account of fossilization, the book synthesizes the major research on the topic, provides a conceptual framework for interpreting various manifestations of lack of learning, and explores the relationship between instruction and fossilization, an issue of extensive interest to second language researchers and educators.

In the preparation for this book, I have benefited, in no small measure, from discussions on various issues with the following individuals (in alphabetical order): David Birdsong, William Davies, Robert DeKeyser, Lynn Eubank, Susan Foster-Cohen, Gillies Houghton, Jan Hulstijn, Scott Jarvis, Eric Kellerman, Donna Lardiere, Diane Larsen-Freeman, Mike Long, Brian MacWhinney, Terry Odlin, Bonnie Schwartz, Tom Scovel, Larry Selinker, Mike Sharwood Smith, Rex Sprouse, and Paul Wiita, though I should point out that none of them is responsible for any of the ideas presented in this book.

Many other individuals have also provided valuable support in various forms, and I am grateful to them all.