McDevitt's first published story was "The Emerson Effect" in The Twilight Zone Magazine in 1981. Two years later, he published his first novel, The Hercules Text, about the discovery of an intelligently conceived signal whose repercussions threaten human civilization. This novel set the tone for many of McDevitt's following novels, which focused on making first contact. Frequently this theme is mixed with both trepidation before the unknown and a sense of wonder at the universe.
With The Engines of God (1994), McDevitt introduced the idea of a universe that was once teeming with intelligent life, but contains only their abandoned artifacts by the time humans arrive on the scene. Although it was initially written as a standalone novel, the main character of The Engines of God, pilot Priscilla Hutchins, has since appeared in six more books, Deepsix (2001), Chindi (2002), Omega (2003), Odyssey (2006), Cauldron (2007) and StarHawk (2013). The mystery surrounding the destructive "Omega Clouds" (which are introduced in The Engines of God) is left unexplored until Omega.
McDevitt's novels frequently raise questions which he does not attempt to answer. He prefers to leave ambiguities to puzzle and intrigue his readers: "Some things are best left to the reader's very able imagination." The SF Site's Steven H Silver has written about this:
McDevitt has a (probably unintentional) tendency to give the impression that his novels will go in one direction and then take them in a different direction. Or possibly his background is so well thought out, that throw away lines, or subplots, or minor characters, have enough information behind them to make the reader want to see their story as much as the main plot of the book. While slightly annoying, this is, I've decided, a strength of McDevitt's writing since it shows the depth of his created worlds.
McDevitt went to La Salle University, where a short story of his won the annual Freshman Short Story Contest and was published in the school's literary magazine, Four Quarters. As McDevitt explained in an interview, "I was on my way. Then I read David Copperfield and realized I could never write at that level, and therefore I should find something else to do. I joined the Navy, drove a cab, became an English teacher, took a customs inspector's job on the northern border, and didn't write another word for a quarter-century." McDevitt received a Master's degree in literature from Wesleyan University in 1971. He returned to writing when his wife, Maureen, encouraged him to try his hand at it in 1980. As of 2007[update], McDevitt lives near Brunswick, Georgia. In 2005, he donated his archive to the department of Rare Books and Special Collections at Northern Illinois University.
The short stories "Melville on Iapetus" (1983), "Promises to Keep" (1984), "Oculus" (2002), "The Big Downtown" (2005), "Kaminsky at War" (2006), "Maiden Voyage" (2012), and "The Cat's Pajamas" (2012) are also set in the Academy universe.