John Archibald (PhD, Toronto, Canada) has been Professor of Linguistics at the University of Victoria (Canada) since 2010, following 19 years at the University of Calgary (Canada). He specializes in second language phonology, and is author or editor of seven books and approximately 30 journal articles and book chapters.

Fatih Bayram is a researcher at the University of Portsmouth, UK. His research primarily focuses on heritage language bilinguals. Bayram investigates the acquisition process of home and societal language in childhood in immigrant contexts, outcomes of language development in (young) adulthood, and on‐line processing of the grammatical system during language production and comprehension.

Alessandro G. Benati is Head of School of Languages and Area Studies and Professor of Second Language Acquisition at the University of Portsmouth (UK). He is internationally known for his research in second language learning and teaching, with special emphases on processing instruction. He has a strong publications record with over 15 established monographs and articles in international journals. He has coordinated national and international research projects and he is honorary visiting Professor at York St. John University (UK).

Lara Bryfonski is a PhD candidate in applied linguistics at Georgetown University. Her doctoral research focuses primarily on interaction and corrective feedback in second language acquisition as well as task‐based language teaching and learning. Lara is also a licensed English as a second language (ESL) teacher and has taught ESL in a variety of contexts in the United States and abroad.

Gavin Bui is Associate Professor at the English Department of Hang Seng Management College in Hong Kong. His research interests lie in task‐based language teaching, development of second language (L2) fluency and lexis, and L2 motivation. His recent publications appeared in Language Teaching Research (Sage, 2016) and TESOL Encyclopedia of English Language Teaching (Wiley, 2017).

Heidi Byrnes is George M. Roth Distinguished Professor of German Emerita at Georgetown University. Her research focuses on adult second language literacy acquisition, particularly at the advanced level, with articles, edited and co‐edited books, and special journal issues addressing the development of advanced literacy, particularly in writing. She is a past president of the American Association for Applied Linguistics and is the recipient of numerous professional association awards. She currently serves as editor‐in‐chief of the Modern Language Journal.

Marcus Callies received a PhD in English linguistics from the University of Marburg (Germany). Since 2014 he has been Professor of English Linguistics at the University of Bremen (Germany). His main research interests are learner corpus research with a focus on lexicogrammatical variation, discourse‐functional and pragmatic aspects of advanced learner varieties, and English for academic purposes. He is serving as editor of the International Journal of Learner Corpus Research and vice‐president of the Learner Corpus Association.

Fred R. Eckman holds the rank of University Distinguished Professor in the Department of Linguistics at the University of Wisconsin‐Milwaukee. Eckman’s major research interest is in second language (L2) acquisition, and has centered mainly on L2 phonology, with a secondary focus on L2 syntax, and L2 acquisition theory. His writings have appeared in a number of anthologies and professional handbooks, as well in several journals, including Applied Linguistics, Language Learning, Second Language Research, and Studies in Second Language Acquisition.

Gregg Fields is a doctoral student in Writing, Rhetorics, and Literacies at Arizona State University‐Tempe. His research interests include second language writing, language identity, metacognition, writing pedagogies, and writing program administration.

Susan M. Gass is University Distinguished Professor at Michigan State University. She has published more than 30 books and more than 150 articles in the field of second language acquisition, with works translated into Russian, Korean, and Chinese. She is the co‐author (with Alison Mackey) of Second Language Acquisition: An Introductory Course of Second Language Research: Methodology and Design. She is the winner of local, national, and international awards. She has served as the president of the American Association for Applied Linguistics and the Association Internationale de Linguistique Appliquée and is currently co‐editor of Studies in Second Language Acquisition.

Kimberly L. Geeslin is Professor at Indiana University in the Department of Spanish and Portuguese. Her research focuses on second language Spanish and the intersection of second language acquisition and sociolinguistics. She is co‐author (with Avizia Lim Yong) of Sociolinguistics and Second Language Acquisition (Routledge, 2014) and the editor of The Handbook of Spanish Second Language Acquisition (Wiley‐Blackwell, 2013). She has published research articles in Studies in Second Language Acquisition, Language Learning, Hispania, Spanish in Context, Bilingualism: Language and Cognition, Linguistics, and Studies in Hispanic and Lusophone Linguistics.

Burcu Gokgoz‐Kurt (PhD, University of South Carolina, 2016) is currently a faculty member at Dumlupınar University (Turkey). Her research focuses on the acquisition of second language (L2) phonology, pronunciation instruction, L2 speech perception, and cognitive aspects of L2 processing. Her doctoral work investigated the effects of training in learning word‐boundary palatalization as a connected speech phenomenon in L2 English in relation to attention control. She has extensive experience teaching English as a foreign language and English as a second language in the United States and Turkey.

Gisela Granena is an Assistant Professor in the School of Languages of the Universitat Oberta de Catalunya (Spain). She has published research on the role of cognitive aptitudes in both instructed and naturalistic contexts; aptitude‐treatment interactions; task‐based language teaching; measures of implicit and explicit language knowledge; and the effects of early and late bilingualism on long‐term second language achievement. Recent publications include Sensitive Periods, Language Aptitude, and Ultimate L2 Attainment (John Benjamins, 2013) and Cognitive Individual Differences in Second Language Processing and Acquisition (John Benjamins, 2016).

Aarnes Gudmestad is Associate Professor in the Department of Modern and Classical Languages and Literatures at Virginia Polytechnic Institute and State University. Her research focuses on the intersection between second language acquisition and sociolinguistics. Current projects address issues pertaining to morphosyntactic structures in native and second language Spanish and French. She has published articles in journals such as Language Learning, Studies in Second Language Acquisition, Studies in Hispanic and Lusophone Linguistics, and Canadian Journal of Linguistics.

D. Eric Holt (PhD, Georgetown University, 1997) is Associate Professor of Spanish and Linguistics at the University of South Carolina. Scholarly work treats phonological theory, language variation and change, Hispanic sociolinguistics, and language acquisition, particularly of connected speech phenomena in Spanish by English‐speaking learners.

Tania Ionin is an Associate Professor of Linguistics at the University of Illinois at Urbana‐Champaign. Her main areas of research are second language acquisition of semantics, with a focus on the nominal domain (definiteness, specificity, genericity, and the mass/count distinction), and experimental semantic investigations of quantifier scope and the interpretation of indefinites in Russian and English.

Sihui Echo Ke is an Assistant Professor at the University of Kentucky. Her recent research has focused on the contributions of morphological awareness to adult and child second language reading.

Keiko Koda is a Professor in the Department of Modern Languages at Carnegie Mellon University. Her research interests include second language reading, biliteracy development, and foreign language instruction and assessment.

Tanja Kupisch is Professor of Linguistics at the University of Konstanz and Professor II in the Language Acquisition, Variation and Attrition (LAVA) research group at UiT The Arctic University of Norway. Her research focuses on first, second, and third language acquisition, early bilingualism, and bilectal language acquisition. She has worked on various aspects of DP syntax, such as article omission, genericity, nominal gender, and adjective placement, as well as on pronunciation.

Terje Lohndal is Professor of English Linguistics at NTNU Norwegian University of Science and Technology, and Adjunct Professor at UiT The Arctic University of Norway. He also co‐directs the AcqVA research group, which focuses on language acquisition, variation, and attrition. Lohndal attempts to identify the basic building blocks of language based on evidence from acquisition, linguistic variation, and attrition, focusing in particular on syntax and its interfaces with morphology and semantics.

Michael H. Long is Professor of Second Language Acquisition at the University of Maryland. The author of over 100 journal articles and book chapters, recent publications include The Handbook of Second Language Acquisition (Blackwell, 2003), Second Language Needs Analysis (CUP, 2005), Problems in SLA (Erlbaum, 2007), The Handbook of Language Teaching (Wiley‐Blackwell, 2009), Sensitive Periods, Language Aptitude, and Ultimate L2 Attainment (John Benjamins, 2013), and Second Language Acquisition and Task‐Based Language Teaching (Wiley‐Blackwell, 2015).

Cristóbal Lozano (PhD, Essex University, UK) has worked on second language acquisition as a teaching fellow (Essex University), a postdoctoral researcher (Universidad Autónoma de Madrid, Spain), and a Fulbright visiting researcher (Pennsylvania State University). He has been Associate Professor of Applied Linguistics at the Universidad de Granada (Spain) since 2010. His research focuses on the second language Spanish and English acquisition of phenomena at the syntax–discourse interface by combining corpus and experimental methods. He directs the CEDEL2 corpus (Corpus Escrito del Español L2).

Paul A. Malovrh is Associate Professor of Hispanic Linguistics and Second Language Acquisition at the University of South Carolina. His research focuses on the potential and limitations of foreign and second language (L2) instruction in interlanguage development, with emphasis on L2 processing strategies across different instructional contexts. His recent work emphasizes advanced‐level language proficiency, in particular, and explores its relationship with globalization and curricular design.

Paul Kei Matsuda is Professor of English and Director of Second Language Writing at Arizona State University. Co‐founding chair of the Symposium on Second Language Writing and editor of the Parlor Press Series on Second Language Writing, Paul has published widely in various edited collections as well as journals such as College Composition and Communication, College English, English for Specific Purposes, International Journal of Applied Linguistics, TESOL Quarterly, and Written Communication.

Fátima Montero is a PhD student in the Second Language Acquisition (SLA) program at the University of Maryland. Her research interests include English and Spanish instructed SLA, maturational constraints, implicit and explicit second language learning, negative feedback, individual differences, and Spanish applied linguistics.

Alfonso Morales‐Front is Associate Professor in the Department of Spanish and Portuguese at Georgetown University. His research interests focus on prosodic aspects of Spanish phonology (syllable, stress, and intonation), the acquisition of first and second language phonology, and study abroad.

Nina Moreno is Associate Professor of Spanish at the University of South Carolina. Her areas of expertise include teacher education, Spanish applied linguistics, cognitive processes in language learning, and computer‐assisted language learning. She has published articles and software reviews in journals such as Language Learning, Foreign Language Annals, and CALICO, and co‐authored Introducción a la lingüística hispánica actual: teoría y práctica (Routledge, 2017).

Matthew E. Poehner is Associate Professor of World Languages Education and Applied Linguistics at The Pennsylvania State University. His research examines Dynamic Assessment, Mediated Development, and Systemic Theoretical Instruction, derived from Vygotsky’s Sociocultural Theory, as a basis for second language educational practice. His most recent book (co‐authored with J. P. Lantolf) is Sociocultural Theory and the Pedagogical Imperative in L2 Education: Vygotskian Praxis and the Research/Practice Divide (Routledge, 2014).

Leah Roberts is Professor of Psycholinguistics in the Department of Education, and Leader at the Centre for Research in Language Learning and Use, at University of York (UK). Her research focuses on second language learning and processing at the word, sentence and discourse levels. Her recent research topics include what adult and child learners can acquire after only limited exposure to a new language, as well as the ways in which two languages interact in the mind of functionally bilingual speakers during real‐time language comprehension.

Jason Rothman is Professor of Multilingualism and Language Development in the School of Psychology at the University of Reading (UK) and Professor II of Linguistics in the Language Acquisition, Variation and Attrition (LAVA) research group at UiT The Arctic University of Norway. His work is grounded within the generative conceptualization of mental linguistic representation and computation, investigating language acquisition and processing in children and adults’ native and non‐native language. Recent work appears in Studies in Second Language Acquisition, Second Language Research, Bilingualism: Language and Cognition, Language, Cognition and Neuroscience.

Marianna Ryshina‐Pankova is Associate Professor of German at Georgetown University. As Director of Curriculum she is actively involved in the maintenance, evaluation, and renewal of the undergraduate curriculum and in mentoring graduate students teaching in the program. Her research interests include application of systemic functional theory to the study of second language (L2) writing development and advanced literacy assessment, as well as L2 pedagogy and content‐ and language‐integrated curriculum design.

Kazuya Saito is a lecturer in the Department of Applied Linguistics and Communication at Birkbeck, University of London (UK). His research interests include how second language learners develop various dimensions of their speech in naturalistic settings, and how instruction can help optimize such learning processes in classroom contexts.

M. Rafael Salaberry (PhD, Cornell University, 1997) holds an appointment as Mary Gibbs Jones Professor of Humanities at Rice University. He is a Professor of Spanish Linguistics and Second Language Acquisition in the Department of Spanish and Portuguese and he is also the Director of the Center for Languages and Intercultural Communication (CLIC) at Rice University.

Cristina Sanz (PhD, University of Illinois at Urbana‐Champaign) is Professor of Spanish Linguistics and Director of Spanish Programs. An expert on multilingual development and education, she is interested in the interaction between context, including study abroad and computer‐assisted learning, and individual differences, especially the role of prior experience and sociocognitive variables in second language development. She has published over 80 books, articles, and chapters; her volume Mind and Context in Adult Second Language Acquisition: Methods, Theory, and Practice (Georgetown University Press, 2005) received the Modern Language Association’s Mildenberger Prize.

Peter Skehan is Professorial Research Fellow at St. Mary’s University (UK), having previously worked at the University of Auckland (New Zealand), the Chinese University of Hong Kong, and King’s College, London, amongst others. His research areas are foreign language aptitude and second language acquisition, especially task‐based learning and performance. His recent publications include a chapter in the Annual Review of Applied Linguistics (2016) and an article on aptitude and grammar in Applied Linguistics (2015).

Roumyana Slabakova is Professor and Chair of Applied Linguistics at the University of Southampton (UK) and is Professor at UiT The Arctic University of Norway. Her research interests focus on the second language acquisition of meaning—more specifically, phrasal‐semantic, discourse, and pragmatic meanings. Her monographs include Telicity in the Second Language (John Benjamins, 2001) and Meaning in the Second Language (Mouton de Gruyter, 2008). She co‐edits the journal Second Language Research and is the co‐author (with Naoko Taguchi) of Second Language Pragmatics (Oxford University Press, 2017).

Naoko Taguchi is a Professor in the Department of Modern Languages at Carnegie Mellon University where she teaches courses in second language acquisition and Japanese language/culture. She is the author of Context, Individual Differences, and Pragmatic Development (Multilingual Matters, 2012) and Developing Interactional Competence in a Japanese Study Abroad Program (Multilingual Matters, 2015), and the co‐author (with Roumyana Slabakova) of Second Language Pragmatics (Oxford University Press, 2017).

Julio Torres (PhD, Georgetown University) is an Assistant Professor of Applied Linguistics in the Departments of Spanish and Portuguese and Linguistics at the University of California, Irvine. He is also the director of the Spanish language program, and is affiliated with the National Heritage Language Resource Center at UCLA. His research interests include heritage/second language acquisition, bilingualism, cognition, and task‐based language learning.

Zhan Wang is Assistant Professor at the Center for Language Education at the South University of Science and Technology in China. She received a PhD in Applied Linguistics from The Chinese University of Hong Kong and completed postdoctoral training at the University of Pittsburgh and Pittsburgh Science of Learning Center. Her research interests include task‐based language teaching, psycholinguistics, and computer‐supported collaborative learning.

Stuart A. Webb is a Professor of Applied Linguistics at the University of Western Ontario (Canada). Before teaching applied linguistics, he taught English as a foreign language in Japan and China for many years. His research interests include vocabulary, second language acquisition, and extensive reading, listening, and viewing. His latest book (co‐authored with Paul Nation), How Vocabulary is Learned, was published by Oxford University Press in 2017.

Marit Westergaard is Professor of English Linguistics at UiT The Arctic University of Norway and Adjunct Professor at NTNU Norwegian University of Science and Technology. She is also head of the LAVA/AcqVA research groups (Language Acquisition, Variation and Attrition). She has published widely in first as well as second/third language acquisition, multilingualism in children and adults, and diachronic change, mainly focusing on linguistic properties such as word order and grammatical gender.

Paula Winke is an Associate Professor at Michigan State University. She teaches language teaching methods and language assessment in the Second Language Studies, TESOL, and Applied Linguistics Program within the School of Language Sciences & Literary and Cultural Studies. She researches language assessment issues and how individual differences affect second language acquisition. She is a former president of the Midwest Association of Language Testers (MwALT) and in 2012 received the TESOL Award for Distinguished Research.

Feng Xiao is Assistant Professor of Asian Languages and Literatures at Pomona College, Claremont, California. His research interests include pragmatics, second language acquisition, bilingualism, and Chinese linguistics.

Nicole Ziegler is Assistant Professor of Second Language Studies at the University of Hawai’i at Mānoa. Her research program focuses on instructed second language acquisition (ISLA), including mixed method and interdisciplinary research in second language conversational interaction, task‐based language teaching, and computer‐assisted language learning, specifically synchronous computer‐mediated communication.

The inception of the present volume goes back to the summer of 2015, when we had a conversation regarding the growing need for advanced‐level users of foreign language in the private and public sectors in an increasingly globalized world. Our conversation quickly evolved into a list of questions regarding what we really know (and do not know) about advanced proficiency in the field of second language acquisition (SLA). While extensive research had been conducted on the topic, we understood that more questions than answers remained. Previous research had already established various frameworks for pursuing the investigation of advanced proficiency and had posited specific questions to be addressed; this volume merely attempts to bring together some of the ways in which such questions are being explored by many of the field’s leading scholars, with the aim of drawing further attention to the need for a greater understanding of higher levels of language use. A search of key terms using any search engine will continuously yield a list of names of scholars who have dedicated their attention to pursuing the topic—names such as Byrnes, Maxim, and Ortega, to name but a few—and we acknowledge that, without their seminal work, the present volume could never have been realized. Their work provided us with the basic structure of the volume, as well as the specific themes to be explored, and we are grateful for their contributions to the field of SLA.

When we first presented our idea for the edited volume to Wiley, the initial response was extremely encouraging, and our proposal was quickly polished and submitted for review. The reviewers’ responses were unanimous: the need for a comprehensive collection addressing advancedness in SLA, in terms of varying theoretical approaches, multiple perspectives and orientations to context, tasks, and learner profiles, phonological and grammatical development, genre, and socially situated use, was long overdue. We were then fortunate enough to bring on board an impressive list of scholars to contribute their expertise to the volume. We, therefore, wish to thank first and foremost, the editorial and production teams at Wiley. Tanya McMullin, our acquisitions editor, provided us with continued guidance and feedback to keep the project on schedule. Manish Luthra, our production editor, and Giles Flitney, our copy‐editor, were continuously available to provide advice regarding formatting issues throughout the editing process. In addition, we thank the outstanding and wonderful contributors who shared their expertise and research in each chapter of the collection. In all cases, we found the editorial process to be enjoyable, as we received nothing short of complete professionalism and cooperation from those whose work comprise the present volume. In short, the project is indebted to the wonderful support of the Wiley team and to the scholars who contributed to it.

As is the case with any volume of this breadth and depth, a considerable amount of time was devoted to editing and peer review. To that end, we wish to thank a number of individuals who selflessly provided their insight and thoughtful feedback in order to maintain a high quality of work in the final draft. They are:

We close our acknowledgement with mention of some of those who have been instrumental in the successful completion of the present volume, through their support and sacrifices, and through their understanding of the importance of our work. They include department chairs, such as Dr. Nicholas Vazsonyi at the University of South Carolina, who acknowledges the important work of his SLA professors through his support for and enthusiasm toward projects such as this. They also include colleagues, such as Professor Matthew Weait, and all members of CARILSE (Centre for Applied Research and Innovation in Language Sciences and Education) at the University of Portsmouth (UK), who understood the value of this project and provided their support and excellent advice throughout. And they include our loving families, our spouses in particular, who have come to know far more about SLA than they probably ever expected to, through their ongoing support of (and interest in) our work. And, finally, they include our graduate students, whose curiosity and thoughtful questions regarding acquisition and advanced proficiency provide a constant motivation for learning more about such topics. We dedicate this volume to them, and to all scholars who strive to understand more about second language acquisition.