Defining lexical familiarizations as devices by means of which an author gives a reader an understanding of newly introduced key lexis, this paper discusses familiarizations in content area textbooks. The various sections of the paper examine the following topics: (1) the forms taken by lexical familiarizations, including use of reader experience, definition and illustration, synonym, contrast with a more common meaning, and restatement in comprehensive terms; (2) prepublication aspects of lexical familiarization, such as the importance of a typographic system, appropriate choice of lexical items to be familiarized, appropriate choice of lexis, and the use of polysemous words and surface structures; and (3) the pedagogic implications of lexical familiarization for the content area specialist and the English specialist, and for textbook selection and examinations in the English language. (FL)