The best place to access a Houghton Mifflin answer key is a Houghton Mifflin textbook. If that textbook has associated online resources, you may be able to access additional resources and answer keys through the Houghton Mifflin reference link provided in the textbook.
How and where to access an answer key for one of Houghton Mifflin's textbooks depends greatly on the specific textbook. Several of Houghton Mifflin's current textbooks have been adapted to include online resources and answers. Access to these resources and answer keys may be restricted by the use of a code provided in the textbook or the use of a unique link.