This edited book is a collection of studies on protolanguage phonology, referring to the development of children’s autonomous linguistic systems from their first meaningful forms to complete cognitive and articulatory acquisition of language. The volume comprises chapters on child bilingual phonological development, understood as the acquisition or use of more than one linguistic code, whether actual languages, dialects, or communication modes, in an array of contexts. Such contexts include endogenous and exogenous bilingualism, heritage language, bilectalism, trilingualism, and typical and atypical use. The contributed works here will be of interest to researchers and postgraduate students investigating language acquisition in bi-/multilingual settings, as well as those working on child phonological development across a variety of languages.

Elena Babatsouli is the Ben Blanco Memorial/BORSF Endowed Professor in Communicative Disorders and an Associate Professor at the University of Louisiana at Lafayette, USA. She is Editor-in-Chief of the Journal of Monolingual and Bilingual Speech (Equinox), Associate Editor of the Journal of Child Language (Cambridge Core), in the Executive Committee of the International Association for the Study of Child Language, and a referee of the European Research Council Executive Agency Consolidator Grant. Dr. Babatsouli also serves on the American Speech-Language-Hearing Association’s Multicultural Issues Board. Her research and scholarship focus on cross-linguistic monolingual and multilingual acquisition/use by children and adults in typical and disordered speech contexts, having published in journals, edited volumes, and encyclopedias. Among several edited/co-edited books (like On Under-reported Monolingual Child Phonology (2020) Multilingual Matters) journal special issues, and conference proceedings, she has recently published Multilingual Acquisition and Learning: An Ecosystemic View to Diversity (2024) for John Benjamins.

Martin J. Ball is Honorary Professor at the University of Bangor, Wales. He is a lead journal and book-series editor and a prominent figure in clinical linguistics/phonetics with numerous monographs and edited books, including most recently Grammatical Profiles: Further Languages of LARSP (co-edited with Paul Fletcher and David Crystal, Multilingual Matters).