Lois Duncan grew up in Sarasota, Florida, the daughter of internationally known magazine photographers, Joseph and Lois Steinmetz. She has one younger brother. From early childhood, she knew she wanted to be a writer. She submitted her first story to a magazine at the age of ten and made her first sale at thirteen to a magazine called Calling All Girls. Throughout her high school years she wrote regularly for young people's magazines, particularly Seventeen.

In 1962, Lois moved to Albuquerque, New Mexico, where she taught for the Journalism Department at the University of New Mexico and continued to write for magazines. Over 300 of her articles and short stories appeared in such publications as Ladies Home Journal, Redbook, McCall's, Good Housekeeping, and Reader's Digest, and for a number of years she was a contributing editor for Woman's Day.

Lois is also the author of 48 books, ranging from children's picture books to adult novels, but she is best known for her young adult suspense novels. Many of those have been chosen as American Library Association "Best Books for Young Adults" and Jr. Literary Guild Selections, and they have won Young Readers Awards in 16 states and three foreign countries. In 1992, Lois received the Margaret A. Edwards Award, presented by the School Library Journal and the Young Adult Library Services Association, to honor a living author for a distinguished body of adolescent literature.

Lois has also written novels and non-fiction books for adults, including Who Killed My Daughter?, the true story of her search for the truth behind the brutal murder of the youngest of her five children, eighteen-year-old Kaitlyn. Although written for adults, this book has been embraced by young people.

Lois is married to Don Arquette.