This volume combines a discussion of bilingual education in three parts of the world, the Soviet Union, the Celtic countries of Western Europe, and the United States, with an outline of a theory of bilingualism and bilingual education. The first part of the book investigates how various systems derive from different combinations of identical elements. The identification of variables is undertaken along with an analysis of the social and linguistic environment of the communities in which the bilingual programs are set. Part Two "Case Studies," is on the historical development and the current extent of multilingualism in the Soviet Union, the Celtic countries, and the United States. This section of the book deals with the primary and secondary variables that have to do with the causes of direct contact between different groups and with the nature of the contact that has been established. The final section of the book deals with justifications of bilingual education, that is, a consideration of attitudes and rationales for languages and bilingual education. It includes discussion of attitudes to languages in contact, and of needs, policies, and programs in bilingual education. Appendices provide a critique of the use of census returns in such a study, and an outline of the structure of bilingual education in Welsh Elementary Schools. (AMH)