The Flesch-Kincaid (F-K) Reading Grade Level (RGL) was developed under contract to the United States Navy in 1975 by J. Peter Kincaid and his team. Other related US Navy research directed by Kincaid delved into high tech education (for example, the electronic authoring and delivery of technical information); usefulness of the Flesch-Kincaid readability formula; computer aids for editing tests; illustrated formats to teach procedures; and the Computer Readability Editing System (CRES).
The F-K RGL formula was first used by the US Army for assessing the difficulty of technical manuals in 1978 and soon after was incorperated into a Department of Defense military standard . The commonwealth of Pennsylvania was the first state in the US to require that automobile insurance policies be written at no higher than a "ninth-grade level" of reading difficulty, as measure by the RGL formula. This is now a common requirement in many other states and for other legal documents such as insurance policies. Today the F-K RGL formula is ubiquitous, and variations of the formula are used with more than a dozen languages. Microsoft Word still uses many of the style and grammar rules first developed for the CRES program.
- Kincaid, J. P.; et al. (1975-02). "Derivation Of New Readability Formulas (Automated Readability Index, Fog Count And Flesch Reading Ease Formula) For Navy Enlisted Personnel". Chief of Naval Technical Training: Naval Air Station Memphis. Retrieved 2011-06-03. Check date values in:
- Kincaid JP, Braby R, Mears J (1988). "Electronic authoring and delivery of technical information". Journal of Instructional Development. 11: 8–13.
- McClure G (1987). "Readability formulas: Useful or useless. (an interview with J. Peter Kincaid.)". IEEE Transactions on Professional Communications. 30: 12–15.
- Kincaid JP, Braby R, Wulfeck WH II (1983). "Computer aids for editing tests". Educational Technology. 23: 29–33.
- Braby R, Kincaid JP, Scott P, McDaniel W (1982). "Illustrated formats to teach procedures". IEEE Transactions on Professional Communications. 25: 61–66.
- Kincaid JP, Aagard JA, O'Hara JW, Cottrell LK (1981). "Computer Readability Editing System". IEEE Transactions on Professional Communications. 24 (1): 38–42.
- MIL-M-38784B. (1983-04-16). "Manuals, Technical: General Style And Format Requirements". Retrieved 2011-06-04.