Harcourt was an American publishing firm with a long history of publishing fiction and nonfiction for adults and children. The company was last based in San Diego, California, with editorial/sales/marketing/rights offices in New York City and Orlando, Florida, and was known at different stages in its history as Harcourt Brace, & Co. and Harcourt Brace Jovanovich. From 1919 to 1982, it was based in New York City.

Houghton Mifflin acquired Harcourt in 2007. It incorporated the Harcourt name to form Houghton Mifflin Harcourt. As of 2012, all Harcourt books that have been re-released are under the Houghton Mifflin Harcourt name. The Harcourt Children's Books division left the name intact on all of its books under that name as part of HMH.

In 2007 the U.S. Schools Education and Trade Publishing parts of Harcourt Education were sold by Reed Elsevier to Houghton Mifflin Riverdeep Group. Harcourt Assessment and Harcourt Education International were acquired by Pearson, the international education and information company, in January 2008.

The first-created component of what would eventually become Harcourt was the World Book Company (unrelated to the Chicago-based World Book, Inc. publisher of reference works), which opened its first office in Manila in 1905 and published English-language educational materials for schools in the Philippines. The company later moved to New York City, where it became a test publisher. Much of the company's success was based on the work of Arthur S. Otis. He was best known for the intelligence tests he developed for the U.S. Army. Millions of World War I draftees took Otis tests.

World Book Company became the first publisher of group-administered tests measuring mental ability when it published Otis's Group Intelligence Scale in 1918. Otis became a World Book employee in 1921. By 1960, World Book had a portfolio of educational tests, including the Stanford Achievement Test (1923), the Metropolitan Achievement Test (1932) and the Otis Mental Ability Test (1936).

Alfred Harcourt and Donald Brace were friends at Columbia College of Columbia University in New York, from which they both graduated in 1904. The two worked for Henry Holt and Company before founding their own publishing company in 1919, Harcourt, Brace & Howe, along with editor Will David Howe. After Howe left the company in 1921, the partners changed the name to Harcourt, Brace & Company. They published the works of a number of writers who became internationally renowned, including Walter Lippmann, Sinclair Lewis, Virginia Woolf, T. S. Eliot, James Thurber, George Orwell, Valentine Davies and Robert Penn Warren. Firms acquired by Harcourt, Brace include Brewer, Warren and Putnam; and Reynal & Hitchcock.

Harcourt, Brace & World only existed between 1960 and 1970. The name Harcourt, Brace & World was used on books that were copyrighted as early as 1931, if not before. By 1960, Harcourt Brace led the market in high school textbook publishing, but had little presence in the elementary school market. That year, William Jovanovich, who had become president of the company in 1954, took the company public and merged Harcourt Brace & Company with World Book Company to create Harcourt, Brace & World, Inc.

This strategic action improved the position of Harcourt Brace because World Book was an established elementary textbook publisher and test publisher.