This volume offers a synthetic approach to language variation and language ideologies in multilingual communities. Although the vast majority of the world's speech communities are multilingual, much of sociolinguistics ignores this internal diversity. This volume fills this gap, investigating social and linguistic dimensions of variation and change in multilingual communities. Drawing on research in a wide range of countries (Canada, USA, South Africa, Australia, Papua New Guinea, Solomon Islands, Vanuatu), it explores: connections between the fields of creolistics, language/dialect contact, and language acquisition; how the study of variation and change, particularly in cases of additive bilingualism, is central to understanding social and linguistic issues in multilingual communities; how changing language ideologies and changing demographics influence language choice and/or language policy, and the pivotal place of multilingualism in enacting social power and authority, and a rich array of new empirical findings on the dynamics of multilingual speech communities.