In our increasingly multilingual modern world, understanding how languages beyond the first are acquired and processed at a brain level is essential to design evidence-based teaching, clinical interventions and language policy. Written by a team of world-leading experts in a wide range of disciplines within cognitive science, this Handbook provides a comprehensive overview of the study of third (and more) language acquisition and processing. It features 30 approachable chapters covering topics such as multilingual language acquisition, education, language maintenance and language loss, multilingual code-switching, ageing in the multilingual brain, and many more. Each chapter provides an accessible overview of the state of the art in its topic, while offering comprehensive access to the specialized literature, through carefully curated citations. It also serves as a methodological resource for researchers in the field, offering chapters on methods such as case studies, corpora, artificial language systems or statistical modelling of multilingual data.

This book aims to bridge the gap in investigations into the acquisition of phonology from a multilingual perspective. In order to fully understand this process, the editors present state of the art research into third language (L3) phonology as well as future considerations for this field. The individual contributions address limitations apparent in current literature, in terms of methodology and scope, while offering innovative solutions in the study of conceptualization, design and data analysis, and novel application of theoretical frameworks to L3 phonology. The contributions consist of a number of original studies which attempt to address vital research questions regarding a bilingual advantage for subsequent phonological acquisition, the variables that drive phonological transfer at the onset of third language acquisition, the L3 developmental path, and how L3 phonological acquisition affects existing systems. The empirical and theoretical strides made in the study of L3 phonology, provided in this volume, confirm that it is a promising area of inquiry with a growing potential to provide novel insights into the linguistic and cognitive underpinnings of language acquisition. This book was originally published as a special issue of International Journal of Multilingualism.