Born in Michigan, Sherwin Cody was orphaned at an early age and raised by relatives in New England. He attended the Canterbury district school in New Hampshire, Waltham High School in Massachusetts, and in 1885 to Amherst College, where he studied with John Franklin Genung and worked as a secretary to Amherst President Julius Hawley Seelye.

After graduating from Amherst, Cody worked at various jobs trying to establish himself as a writer. After the failure of a Horatio Alger-style novel called In the Heart of the Hills, he moved to Chicago in 1896. Cody worked at the Chicago Tribune as correspondence education was being initiated at the University of Chicago, and he was assigned to writing a home study course English for the Tribune. In 1903 Cody produced a version of his course in pocket-sized book form as The Art of Writing and Speaking the English Language which he advertised in the business magazine The System and elsewhere.

Historians of business communication list Cody among those establishing modern business communication based on the notions of clarity, correctness, courtesy, and colloquial style.

Marketing his own books and giving personalized correspondence courses in business writing connected Cody with Chicago business leaders and the school reform movement in Chicago and he developed a series of ability tests which became the basis of the Sherwin Cody 100% Self-correcting Course in English Language.

Working with the Ruthrauff and Ryan Advertising Agency and copywriter Maxwell Sackheim, Cody patented his course, franchised it to two Rochester New York businessmen, Walter Paterson and Charles Lennon, and worked with Sackheim to develop an ad campaign that ran for more than 40 years.

Cody’s ad, headlined Do You Make These Mistakes in English? led with class-conscious examples of mistakes in English and concluded its leading paragraph by noting that “Every time they talk or write” many people “show themselves lacking in the essential points of English.” Later Cody’s account was managed by Sackheim protégé Victor Schwab, who treated it as an example of the scientific approach to advertising. Schwab referred to it as “An Advertisement That is Never Changed,” and he gave a ten-year comparison of responses to two different headlines...Do You Make These Mistakes in English? and How to Speak and Write Masterly English, showing that the response rate was near three times better for the ad asking speakers about their mistakes.

Cody’s ads ran in pulp magazines, slick magazines, comic books and newspapers, and while not literally an advertisement that never changed, it remained remarkably consistent and was even featured in an ad for the Schwab and Beatty in the 1950s. Do You Make These Mistakes in English? is routinely listed among the twentieth centuries best advertisements.

Cody and his wife Marian lived near Chicago until the 1920s when they moved to the community of Dobbs Ferry, New York. The had one son, Edward Morrill Cody (1901-1987), who served in the U.S. Foreign Service from 1941 through 1976, serving as the Deputy Director of the U.S. Information Agency under Edward R. Murrow and as a bureau manager for Radio Liberty from 1965 to 1976.

The Sherwin Cody 100% Self-correcting Course in English Language arrived in 25 weekly booklets, each divided into five sections. Composition was on Mondays, spelling on Tuesdays, punctuation on Wednesdays, grammar on Thursdays, and conversation and literature on Fridays. The daily lessons were tied to other reference books published by Cody including his Nutshell Library, a collection of pocket books excerpting the works of great writers, supplemented the literary studies.

The course was a homestudy course in which students identified and corrected individual weaknesses, with Cody selecting issues of spelling, pronunciation, grammar and word usage that were most commonly troublesome. As a business writer, he emphasized practical life goals such as sales, advertising and letter writing.

Cody marketed his course on the English language from 1918 until his illness and death in the late 1950’s, when it was sold to the US School of Music and later discontinued. The course was revised in the 1930’s with an increased emphasis on speaking (perhaps in reaction to Dale Carnegie’s How to Win Friends and Influence People).