Although technical and social engineering and planning have made tremendous progress, an almost prescientific attitude regarding language planning still prevails in some linguistic circles. (Language planning is defined here as the "methodical activity of regulating and improving existing languages or creating new common regional, national or international languages.") A new branch of science dealing with the theory of language planning is advocated as the proper solution to the intricate problems of language planning. This volume, a "first, modest attempt to outline a theory of language planning," discusses principles, methods, and need for language planning; various aspects of morphology, syntax, lexicology, graphemics, tactics; and "interlinguistics." The science of universal language planning, "interlinguistics," aims for an international language. The problems of structuring an efficient "constructed interlanguage," which would be a real universal human language, can only be solved by competent language planners and not by a popular vote by persons who have had only a superficial contact with the subject. The interim use of English, a natural, ethnic language, as a common international language, is recommended by the author (who warns that to try to hasten its acceptance by wide-scale propaganda would arouse opposition due to national jealousy). (AMM)