This article is Robert Gunning's own assessment of the achieve ments of the Fog Index after twenty years of use. Those in terested in readability formulas will be happy to learn a little more not only about the history and development of the Fog Index but about the applica tions that have been made of it in business and industry, and also in newspaper and govern ment work. Mr. Gunning is well aware, of course, of some of the weaknesses of the index, but obviously he also has rea son to be proud of its achieve ments.