Houghton Mifflin Harcourt Learning Technology originally started as Riverdeep Interactive Learning, a publishing house for
educational online and CD-ROM products based in San Francisco and Dublin, Ireland, founded in 1995, Riverdeep was principally
the creation of the Irish ex-investment banker Barry O'Callaghan. O'Callaghan was Riverdeep's CEO and controlling shareholder.
In October 2002, Riverdeep became a private entity when their stock price plummeted below $2 in NASDAQ.