Margaret Peterson Haddix was born in 1964 in Ohio and grew up on a farm. She comes from a family of farmers who are also avid readers, and Haddix developed a love for literature at an early age. She graduated from Miami University in Oxford, Ohio, with degrees in creative writing, journalism, and history. Haddix participated in the university newspaper and took internships at other newspapers. While dreaming of becoming an author, she saw journalism as a more practical career path. Before publishing her first book, Haddix worked as a copy editor, newspaper reporter, community college instructor, and freelance writer. Working as a journalist helped Haddix nurture her imagination and find inspiration in learning about diverse stories, events, and people. She eventually started writing fiction, experimenting with different plots, settings, and characters. 

Haddix decided to pursue a full-time writing career after her husband became a news reporter—she wanted to avoid working as his employee. To support her career transition, she took part-time jobs teaching writing at community colleges and also did some freelance writing. During that time, Haddix wrote several short stories, and her first two books—Running Out of Time (1995) and Don’t You Dare Read This, Mrs. Dunphrey (1996)—were published after several rejections. Since then, Haddix has written more than 40 books for children that have been translated into 20 languages. She says that she writes stories for young readers because literature played a crucial role in her own life when she was a child. Haddix is best known for her two series: Shadow Children (1998-2006) and Missing (2008-2015). Other important works include Double Identity (2005), the Greystone Secrets series (2019-2021), and The Palace Chronicles (1999-2015).