Language has too often been studied in isolation from the social and political conditions in which it is used. The late David Corson, the General Editor of the first edition of the Encyclopedia of Language and Education, held the position that an acute understanding of theory was a necessary prerequisite for action, not an alternative to it, especially if one were hoping to change policies for the better. The contributions in this volume acknowledge the centrality of the politics of language, highlighting the importance of the social and political contexts of language policy and language education. This is one of ten volumes of the Encyclopedia of Language and Education. The Encyclopedia bears testimony to the dynamism and evolution of the language and education field, as it confronts the ever-burgeoning and irrepressible linguistic diversity and ongoing pressures and expectations placed on education around the world.