Who do i contact for questions about houghton mifflin harcourt books? Any questions regarding Houghton Mifflin Harcourt books can be addressed to our Customer Service department.Where is houghton mifflin harcourt located in florida? Address Houghton Mifflin Harcourt 9400 Southpark Center Loop Orlando, FL 32819 888.242.6747 800.567.2714 E-mail Click here for order placement. Saxon Home School. Hours of Operation 9:00 am to 6:00 pm ET M-F. Address Specialized Curriculum Group 9400 Southpark Center Loop Orlando, FL 32819 ...What is the history of the houghton mifflin company? History. Shortly after, Houghton also founded a publishing company with partner George Mifflin. In 1880, Ticknor and Fields and Houghton and Mifflin merged their operations, combining the literary works of writers with the expertise of a publisher and creating a new partnership named Houghton, Mifflin and Company.When did houghton mifflin become a test publisher? History. Soon after 1916, Houghton Mifflin became involved in publishing standardized tests and testing materials, working closely with such test developers as E. F. Lindquist. By 1921, the company was the fourth-largest educational publisher in the United States.