OVERVIEWThe orientation of this review is intensely practical. It is an attempt to describe what we know and what we need to learn in order to build vocabulary programs that are based on reasonably accurate empirical estimates of what students already know, what they need to learn, and what they can be taught. The scope of the review is, of course, limited. It deals largely with reading vocabulary, with studies of school-age children, and with published studies. It does not deal with the early history of vocabulary research, word recognition (a topic reviewed recently by Gough, 1984, andBaumann, 1984), with readability (a topic reviewed recently by Klare, 1984), or with word lists and word frequency (topics that have not been reviewed recently, but which were excluded because of space limitations).Two themes will emerge as the chapter progresses. One is that although we have a good deal of information relevant to vocabulary instruction, there are a number of very basic questions to which we have almost no answers. The other is that there are a number of questions for which relatively definitive answers are possible and that speculative answers to these questions are not sufficient.The first section of this chapter deals with vocabulary size, depth of word knowledge, and assessing word knowledge. The second deals with the effects of vocabulary on reading comprehension and other verbal phenomena, the third with methods of teaching individual words, the fourth with generative vocabulary instruction, and the fifth with the vocabulary instruction currently