Linguistic research at phonological and higher levels is reviewed. At the phonological level controversy centers around the phenomena of linguistic development, including reading, spelling, and pronounceability, and is accompanied by suggestions of how to help a learner cope with these phenomena. At the higher levels of apparent and underlying phrase structure and the semantic structure which goes with them, controversy occurs in such areas as grammaticality and dialectical differences. Implications of the research are that reading teachers must understand a complex set of linguistic principles, must be able to recognize those instances in which each principle is applicable, and must be able to apply appropriate instructional procedures in proper instances. A bibliography is included. (MD)