SLA researchers have long been baffled why native-like attainment, if existent, is rare among adult L2 learners. In this book we have approached the conundrum through the lens of fossilization (Selinker, 1972). Lying under the constellation of insights, facts, and arguments discussed throughout is the view that the observed general lack of success in adult L2 learning is made up of inter-learner and intra-learner variational success/failure. I have argued that maturational constraints and native language interference – both being constants (as opposed to variables) – jointly set a limit to adult learners' ability to learn a second language such that full attainment of L2 competence is virtually impossible, but that linguistic, cognitive, psychological and social variables may interact to yield differential success/failure across and within learners.

In this concluding chapter, I will first recapitulate the main points that emerged from the discussion in the foregoing chapters, and, then, discuss their implications for research and practice. Finally, by way of conclusion, I will pose questions and offer directions for future research on fossilization.

A Synopsis

Our inquiry in fossilization began, in Chapter 1, with an analysis of L2 ultimate attainment, which led to the recognition of three facets thereof: (1) general lack of success, (2) differential success and failure across learners, and (3) differential success and failure within learners. This conception challenges a prevailing, monolithic view that, in essence, equates L2 adult learners' ultimate attainment solely with permanent deviation from the target language (passim the SLA literature). Following our conception, it is possible that among second language learners, there be different ultimate attainments, some being closer to the target than are others. It is also possible that, for the interlanguage system created by every individual learner, there be multiple ultimate attainments corresponding to its various linguistic domains and subsystems, some of which have successfully reached the target and others of which have remained short of it.

Crucially, this conceptualization, modular in nature, has set the stage for the ensuing theorizing about fossilization in this book.