This chapter serves as a foundational resource for understanding the intricate world of bilingualism and its significance in language education. Beginning with a concise definition of bilingualism, we explore its pivotal role in foreign language learning and teaching. The narrative then traces the historical evolution of models of bilingualism, marking the departure from traditional educational paradigms toward dynamic bilingualism. The chapter also dissects unitary translanguaging theory and crosslinguistic translanguaging theory, aligned respectively with the strong and weak versions of translanguaging. The former denies the existence of named languages, while the latter challenges this notion. In the context of foreign language education, the chapter champions a crosslinguistic translanguaging theory-oriented bilingual paradigm, reframing foreign language education by dismantling language hierarchies, exposing power dynamics, and building on prior achievements. Recognising that bilingual language practices vary in monolingual settings, the chapter endorses a bilingual framework for foreign language instruction, spotlighting emergent bilinguals and their language practices. This chapter enriches our understanding of bilingualism and its implications, particularly in foreign language teaching.