An American fiction author, he is best known for Wicked: The Life and Times of the Wicked Witch of the West. The popular book was the inspiration for Wicked, a highly successful Broadway musical.
He earned his Ph.D in English and American Literature from Tufts University. He wrote his dissertation on the subject of children's literature.
In 1987, almost a decade before the publication of his best-known book, he founded a nonprofit organization called Children's Literature New England.
With his spouse, painter Andy Newman, he adopted three children.
Idina Menzel starred in Wicked, the musical based on Maguire's book.