Schmidt was born in Cincinnati, Ohio and graduated from the University of Cincinnati in 1966. He then attended Case Western Reserve University, where he completed his Ph.D. in physics in 1969. After receiving his degree, he became a professor at Heidelberg College in Tiffin, Ohio, teaching physics, astronomy, and science fiction. Schmidt has been editor of Analog Science Fiction and Fact magazine since 1978. Additionally, he has served as a member of the Board of Advisers for the National Space Society and the Science Fiction Museum and Hall of Fame and was Guest of Honor at BucConeer, the 1998 World Science Fiction Convention in Baltimore, Maryland.

His first publication was "A Flash of Darkness" (Analog, September 1968); his first novel was The Sins of the Fathers (serialized in Analog from November 1973 to January 1974); and his first book was Newton and the Quasi-Apple in 1975.

One of his most recent novels, Argonaut (2002), shows an alien invasion from a new angle.

He was nominated for the Hugo Award for Best Professional Editor every year from 1980 through 2006 (its final year), and for the Hugo Award for Best Editor Short Form every year from 2007 (its first year) through 2010 (the present). He has never won.

Fiction Series

• Kyyra
• The Sins of the Fathers (1976)
• Lifeboat Earth (1978) [C]

Novels

• Newton and the Quasi-Apple (1975)
• Tweedlioop (1986)
• Argonaut (2002)

Collections

• Generation Gap and Other Stories (2002)

Anthology series

Analog anthologies

• Analog Yearbook II (1981)
• Analog's Expanding Universe (1986)
• 6 Decades: The Best of Analog (1986)
• The Analog Anthology #1 (1980) also appeared as: Analog's Golden Anniversary Anthology (1981) and Fifty Years of the Best Science Fiction From Analog (1981)
• The Analog Anthology #2 (1982) also appeared as: Analog: Readers' Choice (1982)
• Children of the Future (1982)
• Analog Anthology #4: Analog's Lighter Side (1982)
• Analog Anthology #5: Writers' Choice (1983)
• War and Peace: Possible Futures from Analog (1983)
• Aliens from Analog (1983)
• Writers' Choice, Volume II (1984)
• 'From Mind to Mind: Tales of Communication from Analog (1984)

SF anthologies

• Unknown (1988)
• Unknown Worlds: Tales from Beyond (1988) with Martin H. Greenberg
• Islands in the Sky: Bold New Ideas for Colonizing Space (1996) with Robert M. Zubrin
• Roads Not Taken: Tales of Alternate History (1998) with Gardner Dozois

Short fiction series

• Lifeboat Earth
• A Thrust of Greatness (1976)
• Caesar Clark (1977)
• Pinocchio (1977)
• Dark Age (1977)
• The Promised Land (1978)
• Second Interlude (1978)
• First Interlude (1978)
• Third Interlude (1978)
• Fourth Interlude (1978)
• Prologue (1978)

Short fiction

• A Flash of Darkness (1968)
• The Reluctant Ambassadors (1968)
• . . . And Comfort to the Enemy (1969)
• Lost Newton (1970)
• May the Best Man Win (1971)
• The Unreachable Stars (1971)
• The Prophet (1972)
• His Loyal Opposition (1976)
• Panic (1978)
• A Midsummer Newt's Dream (1979)
• Camouflage (1981)
• Tweedlioop (1981)
• Mascots (1982)
• War of Independence (1982)
• The Folks Who Live on the Hill (1984)
• Floodgate (1988)
• The Man on the Cover (1990)
• Worthsayer (1992)
• Not Even a Chimney (1993)
• Johnny Birdseed (1993)
• The Parallels of Penzance (1998) with Michael A. Burstein
• Good Intentions (1998) with Jack McDevitt
• Generation Gap (2000)
• The Emperor's Revenge (2002)

Nonfiction

• Writing Science Fiction and Fantasy (1991) with Ian Randal Strock and Gardner Dozois and Tina Lee and Sheila Williams
• Aliens and Alien Societies: A Writer's Guide to Creating Extraterrestrial Life-Forms (1996)
• Which Way to the Future?: Selected Essays From Analog (2001)
• The Coming Convergence: Surprising Ways Diverse Technologies Interact to Shape Our World and Change the Future (2008)