In 1959, Hardwick published in Harper's, "The Decline of Book Reviewing," a generally harsh and even scathing critique of book reviews published in American periodicals of the time. The 1962 New York City newspaper strike helped inspire Hardwick, Robert Lowell, Jason Epstein, Barbara Epstein, and Robert B. Silvers to establish The New York Review of Books, a publication that became as much a habit for many readers as The New York Times Book Review, which Hardwick had eviscerated in her 1959 essay.
In the 1970s and early 1980s, Hardwick taught writing seminars at Barnard College and Columbia University's School of the Arts, Writing Division. She gave forthright critiques of student writing and was a mentor to students she considered promising.
From 1949 to 1972 she was married to the poet Robert Lowell. Their daughter is Harriet Lowell.
She was elected a Fellow of the American Academy of Arts and Sciences in 1996. In 2008, The Library of America selected Hardwick's account of Caryl Chessman's crimes for inclusion in its two-century retrospective of American True Crime writing.
She was the author of three novels: The Ghostly Lover (1945), The Simple Truth (1955), and Sleepless Nights (1979). A collection of her short fiction, The New York Stories of Elizabeth Hardwick, was published in 2010. She also published four books of criticism: A View of My Own (1962), Seduction and Betrayal (1974), Bartleby in Manhattan (1983), and Sight-Readings (1998). In 1961 she edited The Selected Letters of William James and in 2000 she published a short biography, Herman Melville, in Viking Press's Penguin Lives series.