Alpha Books, a member of Penguin Random House, is an American publisher best known for its Complete Idiot's Guides series.

Pearson Education acquired Macmillan General Reference (MGR) from Simon & Schuster in 1998 and retained Complete Idiot's Guides while the rest of MGR was sold to IDG Books.

[1] Alpha moved from Pearson Education to Penguin Group in 2003.

Alpha became part of sister company DK in 2012.

[2] As of 2021[update], the Complete Idiot's Guides contains over 120 books.