This concept paper is intended to assist educators to understand why American culture has become so diverse, to review certain guiding principles and related research in effective educational practices for language instruction, and to present a number of instructional implications derived from the research. The recommendations for teachers which are presented in the paper are divided into principles for instruction, for reading, for oral communication, for writing, and for communicating with parents. A 37-item annotated bibliography is attached. (NKA)