Innovative and interdisciplinary in approach, this book explores the role of the mother tongue in second language learning. It brings together contributions from a diverse team of authors, to showcase a range of Francophone perspectives from the fields of linguistics, psychology, cross-cultural psychiatry, psychoanalysis, translation studies, literature, creative writing, the neurosciences, and more. The book introduces a major new concept: the (M)other tongue, and shows its relevance to language learning and pediatrics in a multicultural society. The first chapter explores this concept from different angles, and the subsequent chapters present a range of theoretical and practical perspectives, including counselling case studies, literary examples and creative plurilingual pedagogies, to highlight how this theory can inform practical approaches to language learning. Engaging and accessible, readers will find new ideas and methods to adopt to their own thinking and practices, whether their background is in language and linguistics, psychiatry, psychology, or neuroscience.