Houghton Mifflin Harcourt is an American publisher of textbooks, instructional technology materials, assessments, and reference works. The company is based in the Boston Financial District. It was formerly known as Houghton Mifflin Company, but it changed its name following the 2007 acquisition of Harcourt Publishing. Prior to March 2010, it was a subsidiary of Education Media and Publishing Group Limited, an Irish-owned holding company registered in the Cayman Islands and formerly known as Riverdeep. In 2022, it was acquired by Veritas Capital, a New York-based private-equity firm.

A textbook is a book containing a comprehensive compilation of content in a branch of study with the intention of explaining it. Textbooks are produced to meet the needs of educators, usually at educational institutions. Schoolbooks are textbooks and other books used in schools. Today, many textbooks are published in both print and digital formats.