In a study of the readability of Air Force regulations, the writer-estimated reading grade level (RGL) for each regulation was rechecked by using the FORCAST readability formula. In four of the seven cases, the regulation writers underestimated the RGL of their regulation by more than one grade level. None of the writers produced a document with an RGL much below eleventh grade, while the intended audience's RGL for three of the seven regulations was below tenth grade. In the main portion of the study, about 900 Air Force personnel took cloze and vocabulary tests to determine the comprehensibility of each regulation to its user audience. A criterion of 40% on the cloze score, corresponding to a 75% score on traditional comprehension tests, was set as the standard for adequate comprehension. Mean scores in three fields were clearly above criterion, and the score in one additional field was borderline. Using the term literacy gap to refer to a situation where a text is written at an RGL too high for its intended readers, it was found that in all cases in which there was no such gap, comprehension was adequate. In all these cases, however, audience RGL was also quite high. In three of the four instances where a literacy gap did exist, comprehension scores were below criterion and RGL was low (below 9.2). (RL)