He was the eldest of three sons of Leticia Jane Hargrave Grierson, a Scottish teacher and editor from Edinburgh, and Hellmut Otto Emil Lehmann-Haupt, a German-born graphic arts historian and bibliographer.
[4] He did postgraduate work at the Yale School of Drama, from which he graduated in 1959 with a Master of Fine Arts degree in theater history and dramatic criticism.
[1] He worked as an editor for various New York City publishing houses, among them Holt, Rinehart and Winston and The Dial Press.
In May 1968, along with several dozen then-prominent writers and political activists (including James Baldwin, Jules Feiffer, Norman Mailer, Susan Sontag and Gloria Steinem), Lehmann-Haupt signed the "Violence in Oakland" essay published in the New York Review of Books.
A police attack on April 6, 1968, had resulted in their killing 17-year-old Bobby Hutton, and wounding leaders Eldridge Cleaver and another young African-American man.
He wrote articles on a variety of subjects, including fly fishing and bluegrass banjo-picking, two of his occasional avocations.
In 1980, when given a copy of Harlan Ellison's Shatterday for possible review, Lehmann-Haupt reportedly threw the book across the room and said, "Oh, it's that sci-fi crap.
He was appointed the Editorial Director of Delphinium Books, a literary small press that publishes works of fiction.