The present volume has explored a very wide range of topics within the field of foreign language aptitude with sections covering aptitude test batteries, the testing of diverse groups, innovative perspectives, and pedagogic implications. Each chapter has made a considerable contribution to updating the topic of aptitude. Inevitably, though, the chapters have explored areas that transcend the different heading sections, making new connections and even announcing new areas for aptitude research. The present chapter highlights all of these insights and weaves them into the discussion of a series of themes which emerge, some traditional from established aptitude work and some reflecting the changes we have seen in recent years.

In this introductory chapter, we first provide a brief overview of research paradigms of language aptitude testing and theory construction in the past six decades, summarizing the major achievements and innovations in research methodologies. Following this, we discuss the background and rationale of the current volume, highlighting the key contents of each chapter and evaluating their potential contributions to enhancing our understanding of language aptitude theory and practice. We conclude the introduction by calling upon scholars to work concertedly towards building an integrated language aptitude theory that will allow us to diagnose, predict, and explain the second language learning process and outcomes. Overall, the current volume calls for a paradigm shift of language aptitude research from its previous focus on aptitude testing to theory construction and practical applications.

The chapter first revisits the major developments of MLAT and its variants based on Stansfield & Reed (2019), and then turns to focus on the MLAT-Elementary test battery that was designed particularly for long-neglected groups of young L2 learners, including the history of MLAT-E, its applications and validations over the past five decades, and finally, and outline of its future.

The present chapter has two general aims. The first is to survey the range of aptitude batteries and sub-tests that are discussed in the literature, and then to explore how they relate to one another and what emphases each of them contains. To achieve this, the various sub-tests will be located in terms of two dimensions: whether they are domain-specific or domain-general, and whether they require implicit or explicit processes and learning. In addition, how the different domains of sound, working memory, processing, language and learning are handled in each of the sub-tests will be explored. The second aim is to explore what insights aptitude tests might contribute to theorizing about the nature of second language learning. The different theoretical accounts will be examined, and then existing aptitude tests will be related to them, indicating clear coverage in some areas, and not very much in others. Overall, it is argued that aptitude work, viewed in this way, should be central to second language acquisition and reveal how we can understand and predict it.

The editors of this volume have issued a full-throated call for a paradigm shift in language aptitude research from its predominant focus on test construction for the purpose of predicting success to theory construction that would enable diagnosis and explanation of second language learning processes and outcomes, as well as tailored teaching of foreign languages. The paradigm shift called for is, indeed, timely and of paramount importance. This epilogue revisits the origins of foreign language aptitude testing and the intended purposes of the original language aptitude batteries, especially the MLAT. The approach in this epilogue is to introduce and discuss questions that are key to the paradigm shift from the Carroll era of test construction to contemporary efforts to develop a comprehensive theory of language learning. Overall, it argues that individual chapters of this volume have contributed to demonstrating how the potential links between language aptitude testers and language teachers (the practitioners) can be built through joint efforts to illuminate the underlying processes and outcomes of foreign/second language learning.