Macmillan Inc. was a now mostly defunct American publishing company. Once the American division of the British Macmillan Publishers, remnants of the original American Macmillan are present in McGraw-Hill Education's Macmillan/McGraw-Hill textbooks and Gale's Macmillan Reference USA division. The German publisher Holtzbrinck, which bought Macmillan UK in 1999, purchased most US rights to the name in 2001 and rebranded its American division with it in 2007.^[1]

George Edward Brett opened the first Macmillan office in the United States in 1869 and Macmillan sold its U.S. operations to the Brett family, George Platt Brett, Sr. and George Platt Brett Jr. in 1896, resulting in the creation of an American company, Macmillan Publishing.^[2] Even with the split of the American company from its parent company in Britain, George Brett Jr. and Harold Macmillan remained close personal friends.^[3]

George P. Brett Jr. made the following comments in a letter dated 23 January 1947 to Daniel Macmillan about his family's devotion to the American publishing industry:

Under the leadership of the Brett family, MacMillan served as the publisher of American authors, Winston Churchill,^[4] Margaret Mitchell, who wrote Gone with the Wind,^[5] and Jack London,^[6] author of White Fang and Call of the Wild.

The Bretts remained in control of the American offices of Macmillan from its creation in 1869 to the early 1960s, "a span matched by few other families in the history of United States business."^[3]

Through its merger with Crowell Collier Publishing Company in 1961 and other acquisitions (notably The Scribner Book Companies in 1984), the US publisher became a media giant in its own right, as Macmillan, Inc. It was acquired by the controversial British tycoon Robert Maxwell in 1989 and eventually sold to Simon & Schuster in 1994, in the wake of Maxwell's death (in 1991) and the subsequent bankruptcy proceedings.^[7] (At the time, Viacom had just purchased S&S via the acquisition of its former parent company Paramount Communications; it is now owned by CBS Corporation.) Macmillan Publishing USA became the name of Simon & Schuster's reference division. Pearson acquired the Macmillan name in America in 1998 (and merged Macmillan Computer Publishing with Addison Wesley Longman to form Pearson Tech Group division of Pearson Education), following its purchase of the Simon & Schuster educational and professional group (which included various Macmillan properties).^[1] Pearson sold the Macmillan Reference USA division (which included Scribner Reference) to Thomson Gale in 1999.

Macmillan's school publishing operations were merged into a joint operation with McGraw-Hill in 1989. McGraw-Hill acquired full ownership of Macmillan/McGraw-Hill in 1993 after Maxwell's death.^[8]

Holtzbrinck purchased most of the rights to the Macmillan name from Pearson in 2001,^[9] but not any of the businesses then associated with it. Holtzbrinck rebranded its US division with the name in 2007.^[1]

The online user-maintained database Jacketflap reports these constituent American publishers of Holtzbrinck's Macmillan division (August 2010):^[10]