Sol Stein, a best-selling novelist who later developed software programs for writers but was perhaps best known as the publisher of major works by James Baldwin and Che Guevara, died Sept. 19 at his home in Tarrytown, N.Y. He was 92.

He died of complications from dementia, said his wife, Edith Shapiro.

Mr. Stein had a varied career, beginning in the 1950s with the Voice of America, where he helped formulate anti-communist programming that was broadcast to dozens of countries around the world.

He also wrote plays and moved into publishing, first at Beacon Press, where in 1955 he edited Baldwin’s “Notes of a Native Son,” a collection of essays about the African American experience that became a literary classic.

Mr. Stein had known Baldwin since they were students at DeWitt Clinton High School in the Bronx and staff members on the school literary journal.

“So much happened in our work together that his color disappeared, my color disappeared and it stayed that way for the rest of our lives,” Mr. Stein told the New York Times in 2004.

“I was crazy about Jimmy’s mother,” Mr. Stein said. “She was my second mother. She struck me as colorblind. I never had the feeling I was the white kid visiting. I was Jimmy’s friend.”

In 2004, Mr. Stein wrote “Native Sons” about their friendship and the gen­esis of Baldwin’s book. Mr. Stein included copies of dozens of letters he and Baldwin exchanged during the writing and editing of “Native Son.”

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“These letters, capturing the men at a pivotal moment in their careers and friendship,” critic Wendy Smith wrote in Kirkus Reviews, “remind us that a cultural landmark like ‘Notes of a Native Son’ is also the product of a fallible, questing human being who misspelled words and worried about his relatives just like the rest of us.”

After several years at Beacon, Mr. Stein formed an independent publishing company, Stein & Day, in 1962. His business partner and the corporate vice president was his wife at the time, Patricia Day. Over the next 25 years, Stein & Day published hundreds of books, including works by such well-known figures as David Frost, Jack Higgins, Budd Schulberg, Marilyn Monroe and F. Lee Bailey. The firm’s first major bestseller was “America America,” an autobiographical 1962 novel by film director Elia Kazan, who later made it into a movie.

In 1968, Mr. Stein was caught up in a complex international scramble to publish the diaries of the charismatic Argentine-born revolutionary Ernesto “Che” Guevara. After helping organize Fidel Castro’s takeover of Cuba in the 1950s, Guevara sought to inspire revolutionary movements around the world.

He dropped out of sight for a few years before ending up in Bolivia, where he aimed to build a guerrilla network that would sweep across the South American continent. With help from the CIA, Bolivian military forces captured and killed Guevara in October 1967.

Among his belongings was a diary, which the Bolivian government seized, setting off a bidding war for publication rights. Castro released a truncated copy of the diary that made its way to Cuba, and questions about copyright caused several publishing houses to back away.

Competing versions appeared in magazines and a paperback edition, but in 1968, Stein & Day published “The Complete Bolivian Diaries of Che Guevara” after obtaining rights from the Bolivian government. The book detailed the travels, hopes and struggles of the revolutionary many people considered a martyr.

“Give a thought once in a while,” Guevara wrote to his parents, “to this little twentieth century soldier-of-fortune.”

While publishing the works of others, Mr. Stein had a thriving writing career of his own. He completed his first novel, “The Husband” (1969), in 17 days by rewriting one of his plays. His 1971 novel, “The Magician,” inspired by his childhood interest in magic, was a page-turning legal thriller that sold more than a million copies

“It’s a spectacular read,” critic Webster Schott wrote in the Times. “Stein picks up new characters, spins anecdotes, finds new events as though he had a bottomless hat from which to draw surprises.”

All of Mr. Stein’s nine novels were published by companies other than Stein & Day.

“I have 100 other authors every year,” he said in 1985, “and if I publish myself I am in competition with them.”

Solomon Stein was born Oct. 13, 1926, in Chicago and moved as a child to New York. His father was a jewelry designer, his mother an interpreter who eventually worked for the United Nations.

Mr. Stein entered college at 15, served in the Army during World War II, then graduated in 1948 from the City College of New York. He received a master’s degree in English literature from Columbia University in 1949.

During the early 1950s, he worked at the Voice of America in New York and later became an official at the American Committee for Cultural Freedom, an organization secretly funded by the CIA. The committee, a loosely organized group of leading intellectuals, opposed ideological extremism from both the left and right. Mr. Stein helped edit a book critical of Joseph McCarthy (R-Wis.), the senator who recklessly charged countless government workers with being communist sympathizers.

Mr. Stein wrote two plays in the 1950s that had short Broadway runs, “Napoleon” and “A Shadow of My Enemy,” then worked at Beacon Press before launching Stein & Day.

“Publishing has gotten away from being a cottage industry to be a grouping together of many firms under a corporate umbrella,” he told United Press International in 1985. “We are the last independent to play the bestseller game principally because the large firms shy away from anything that controversial.”

Stein & Day filed for Chapter 11 bankruptcy protection in 1987, then folded two years later.

“I lost $2.8 million — everything I owned except the house I mortgaged heavily, trying to save our company,” Mr. Stein said.

He was deeply embittered by the experience, which he chronicled in a scathing nonfiction book, “A Feast for Lawyers” (1989). Among other choice terms, he called bankruptcy lawyers “human scavengers” and “vulture capitalists.”

His marriages to Sondra Klein and Patricia Day ended in divorce. Survivors include his wife since 2000, Dr. Edith Shapiro; four sons from his first marriage; three children from his second marriage; two stepchildren; nine grandchildren; and two great-grandchildren.

After leaving the publishing business, Mr. Stein wrote several guides to writing and taught in colleges, including the University of California at Irvine. He also developed a software program, WritePro, to teach fiction-writing techniques to aspiring writers. The program sold tens of thousands of copies and led to several spinoffs.

“I’ve had 36 years of editing, and at the same time I’ve had nine novels published,” he said in 1990. “So in a sense what I’ve got is not the attitude of a teacher, or of a failed writer, but that of the craftsman who wants to pass along that craft to others.”

Mr. Stein had a boisterous personality that sometimes clashed with the egos of his authors, including Kazan. They worked for months editing Kazan’s novel “The Arrangement,” about a business executive facing an existential crisis, which became a No. 1 bestseller in 1967. Kazan later made it into a film starring Kirk Douglas and Faye Dunaway.

“There was a period when ‘The Arrangement’ was being written when chairs were being flung around and he wouldn’t talk to me,” Mr. Stein said in 1968. “He wrote me: ‘You bucher, why don’t you go off and write your own book?’

“I wrote back: ‘When you can spell butcher, you can call me a butcher. I’ll write a book when you get your seat off my typewriter.’ So when the chance came I sat down and wrote my own book.”