This updated and revised edition of Hamers and Blanc's successful textbook presents new knowledge about languages in contact from individual bilinguality to societal bilingualism. It is multi- and interdisciplinary in approach, and analyzes bilingualism at individual, interpersonal, and societal levels. Linguistic, cognitive and sociocultural aspects of bilingual development are explored, as are bilingual problems. The authors cover a range of issues including the relationship among culture, identity, and language behavior in multicultural settings; communication strategies in interpersonal and intergroup relations; language shift; pidgins and creoles; language planning; and bilingual education.