Basic words have been defined as those from which other words can be derived semantically. The assumption underlying the instructional utility of a list of basic words is that a knowledge of them would provide a key to the understanding of a much larger set of related words. Although it has been shown that there are far too many basic words in the English language to make a comprehensive list useful instructionally, it has been suggested that a small set of high frequency basic words that students encounter in academic situations would be very useful as a tool for literacy development. Consequently, a study sought to identify a list of K-6 basic words students commonly encounter in content-area textbooks and standardized tests. From an initial corpus of 30,371 words, 6,768 basic words were identified and their grade levels were estimated. This provides for the first time a corpus of basic words that appear to be academically sound and are also few enough to have instructional utility. (One table of data is included; 14 references and an appendix--containing the list of basic words organized by grade level--are attached.) (Author/SR)