The book brings together sociolinguistic, neurolinguistic, and educational perspectives on language acquisition and learning in the classroom and at home. First and second language acquisition studies, classroom research findings, Polish, European and international legislation, as well as statistical reports on foreign language learning and teaching show how learners proceed from monolingual to bilingual or plurilingual competence. The book provides an overview of the major issues in the field from the teacher’s perspective, equipping teachers with theoretical underpinnings related to language education, and inviting reflection on individual choices in promoting bi- and multilingualism.