A study to develop a methodology for discovering how one important notion or semantic category, "frequency of occurrence," is expressed in words, phrases, or other linguistic devices in academic English began with a search for devices expressing that notion, by analyzing text from a news magazine, a New Zealand geography textbook, and a dictionary, and by asking native speakers. Distinctions were made between frequency of occurrence and recurrence, probability, quantity, spatial distribution, and duration, and efforts were made to discover implicit expression of frequency. Almost 300 devices were found, and the Brown corpus of written American English and the parallel LOB corpus of written British English were analyzed by computer for instances of the devices' use. About a third of the devices were not found in the corpora, but a number of other possible types were achieved through the use of attenuators such as "almost" and "nearly," and in combination with quantity words such as "many." It was found that: (1) the technique of asking native speakers about these devices was the most thorough method of discovering the devices; (2) the list is helpful to teachers of English only when it gives information about use in different kinds of texts; (3) the differences between American and British English were not statistically significant; and (4) learners of academic English will encounter many devices for expressing frequency of occurrence, but may have to produce very few. (MSE)