One of a series dealing with current issues affecting language arts instruction, this paper focuses on the conceptions and misconceptions of readability. The paper begins by noting that over the years, researchers in readability have had two major goals: to determine what makes written materials easy or difficult to read and comprehend, and to effect an optimal match between readers and texts. This is followed by a discussion of some of the factors, such as sentence length and vocabulary, that make texts easy or hard to read and understand. The various applications of readability formulas are then examined, with some discussion given to the misconceptions of their use. The paper concludes by noting that scores from readability formulas are no more substitutes for judgment than are scores from reading tests: in both cases, interpretation on the basis of particular conditions is required. (HOD)