Blanche Knopf (1894–1966), known throughout her long publishing career for her chic apparel, would have appreciated her biographer’s smart outfit. When Laura Claridge arrives at the offices of Farrar, Straus and Giroux to discuss the April publication of The Lady with the Borzoi: Blanche Knopf, Literary Tastemaker Extraordinaire, she removes a beautifully tailored white winter coat to reveal an above-the-knee olive-green dress dotted with stars paired with textured tights and black half boots. She’s as convivial as the famously social Knopf as well; within minutes, she’s telling me about her years living in Brooklyn before moving to the Hudson Valley. Claridge also alludes to her not-terribly-happy childhood in Florida and her stint in the Army to pay for her Ph.D.—she is frank without oversharing—before we move on to the main subject.

The Lady with the Borzoi, Claridge’s fourth biography, is the product of a long and tangled publishing history. Decades ago, New Yorker writer Susan Sheehan and Newsday book critic Peter Prescott had, in succession, struggled with a biography of Blanche and her husband Alfred (1892–1984), who together founded the publishing company Alfred A. Knopf in New York in 1915. Sheehan researched the Knopfs through much of the 1970s; Prescott took up the project in the ’80s. Claridge fleshes out the story: “Alfred was still alive when [Sheehan and Prescott] were working, and he threw roadblocks in their way. Susan told me that she just really got sick of it—it was so time-consuming, and she’d spent her entire advance traveling to do interviews. So she sold the papers to Prescott to recover the advance. He had done some good research, but his publisher rejected the initial draft of the manuscript, and I think it was around that time that he died [in 2004]. When I contacted his widow, Anne, she told me to come on over to the apartment, let me loose on his papers, and said, ‘Take as long as you want.’ I’m not sure she was supposed to do it, because the Ransom Center [at the University of Texas at Austin] had been promised all the papers, but when Peter died she didn’t feel under the same constraints.”

Claridge had become intrigued by the Knopfs while taking a break after completing her 2008 biography of etiquette authority Emily Post. “I did my Ph.D. in romantic literature, and, just for pleasure, I had gone back to reading about it,” she says. “I noticed that the Knopfs had published some of the most important books on the romantics that I had read as a student, and I wondered what a biography of them would reveal. So I looked them up, and there was no biography; I still find it hard to believe.” It was the same surprising lack that prompted Claridge’s books on Post, art deco painter Tamara de Lempicka, and iconic American illustrator Norman Rockwell, she says. “It’s always amazing when that happens. First I ask, where is it? The next thought is, if it really isn’t there, why don’t I write it? Then I’m always sure, someone else is thinking of it right now!”

Although Claridge initially intended to write a dual biography of Alfred and Blanche, she became more involved with Blanche as the research progressed. “There was no model for what she did, being the first American female publisher of the 20th century, and the question of how she handled it in a copartnership with her husband is to me very interesting,” Claridge says. Neither Blanche nor Alfred handled the partnership well. Their screaming fights at editorial meetings are publishing legend, but Claridge found plenty more dysfunction. Her decidedly unvarnished portrait shows Alfred to be dismissive of his wife as a publisher and sexually disinterested in her; Blanche retaliated by openly taking a series of high-profile lovers, including violinist Jascha Heifetz and conductor Serge Koussevitzky. Alfred responded on some occasions with physical abuse, attested to by their son Pat in interviews with Sheehan and Prescott. Given the toxic nature of the Knopfs’ marriage, one has to wonder why it endured.

“I’ve thought about that so much,” Claridge says. “According to [Pat] and a couple of people at Knopf, she threatened Alfred several times with leaving. He would say, ‘Okay, you can do that, but you will never again work in this town as a publisher.’ And publishing was her life.”

In Claridge’s view, Blanche’s taste and judgment shaped the firm much more significantly than Alfred’s: “She didn’t do much line editing, but she would read a manuscript very closely, decide whether it was worth pursuing, then once it was acquired and edited she would look over what other people had done. She was literarily very involved, whereas I don’t think Alfred was. He got bored with the company pretty early, and she never did; it was always her baby. Everybody who worked with her as an author adored her: H.L. Mencken and Carl Van Vechten were devoted to her; so were John Hersey and William Shirer. When writers would lament that they just couldn’t do a book, she was the one who would say, ‘I know you can.’ ”

If only, Claridge sighs, editors were so encouraging today. “I sometimes wish for Maxwell Perkins, the way he edited Fitzgerald. He’d say, ‘I think this is great, but if you could just change these words,’ or, ‘You know that title, Trimalchio in West Egg? It’s good, but how about The Great Gatsby?’ I have never had an editor be that careful and kind with me. Nowadays, they’re so hurried—they’ll just say, ‘Oh, that’s stupid.’ ”

Claridge recalls that when she handed in the first two chapters of the Tamara de Lempicka biography, her editor said, “What the hell is this? You can’t just jump around and say this happened, and then it’s 50 years later.” Claridge adds, “Well, I had never written a biography! I was learning on the job, but luckily I’m a quick study.”

It’s not every writer who would tell an anecdote like that about herself, but Claridge has spent too much of her life wrestling health problems to waste time nursing her ego. She had been an English professor at the U.S. Naval Academy for 10 years when a severe gastrointestinal disorder led her to retire early and focus on nonacademic writing in the late 1990s. A decade later, in the middle of work on Emily Post: Daughter of the Gilded Age, Mistress of Manners, Claridge began behaving so strangely that her husband eventually took her to a psychiatrist, who had her admitted to a hospital. An MRI revealed cancer in the brain, and long months of grueling treatments followed.

“By the time I went back to the book I had a lot of thinking and changing to do,” Claridge says. “The doctors told me I wouldn’t write again, but that never occurred to me. My writing group has told me they were really impressed that I never said I wasn’t going to be able to write, I just wanted to get back to it. They wanted me to take more time off, and I said, ‘No. Writing makes me think I’m going to live.’ ”