Winthrop Smith was one of the founders of the Truman and Smith Publishing Company.
In 1833, the company contracted with William Holmes McGuffey, a professor at Miami University in Oxford, Ohio, to produce a series of six schoolbooks. McGuffey completed the first two texts in 1836. He received ten percent of all profits for authoring the books, with his total monetary gain not to exceed a total of one thousand dollars. McGuffey's Readers, as the books became known, sold more than 125 million copies by 1900. It was the most commonly assigned textbook in American schools during the late nineteenth century.
Truman and Smith Publishing Company also produced a mathematics textbook written by Joseph Ray. Ray's book became the most commonly assigned text in mathematics courses during the nineteenth century. In 1841, the Truman and Smith Publishing Company dissolved. Smith established the Winthrop B. Smith Publishing Company and retained the rights to publish McGuffey's Readers. As a result of McGuffey's Readers, Smith became a very wealthy man. In 1891, his company merged with the American Book Company and created the largest textbook publishing company in the world.