Heidi Toffler, who partnered with her husband, Alvin Toffler, to write best-selling books about the future of human society in an age of rapid technological change, but whose contributions as a researcher and editor remained largely unsung until her husband formally outed her as a co-author, died Feb. 6 at her home in Los Angeles. She was 89.

The death was announced by their consulting firm, Toffler Associates, which did not give a cause.

United in a marital and intellectual partnership for more than six decades, the Tofflers described themselves as “a one-family think tank,” whose long-running discussions (and frequent arguments) on economics, technology, war and the environment formed the seeds of about a dozen futurist books. Their aim, they often said, was not to predict the future, but to synthesize events and thus shine a light on what might come next.

“We are pattern detectors,” Alvin Toffler told the New York Times in 1995. Everyone, he added, makes “assumptions about what is going to happen after this moment. The difference between us and others is that most people make these suppositions unconsciously. We do it deliberately — and build models.”

The Tofflers’ first book, “Future Shock” (1970), anticipated the emergence of the personal computer, cable television, the Internet and “that peculiarly super-­industrial dilemma: overchoice,” as evident when consumers are confronted by dozens of varieties of toothpaste in the aisles of a superstore.

“Future Shock” — its title referred to a sense of “too much change in too short a period of time” — sold millions of copies, was translated into dozens of languages and spawned two follow-ups, “The Third Wave” (1980) and “Powershift” (1990), which featured detailed prognostications on cloning, teleworking and virtual reality.

Yet each book was credited to just one author, Alvin Toffler. While Ms. Toffler accompanied her husband on book tours and joined him for interviews, the extent of her contributions remained little known before the publication of “Powershift.”

“This entire trilogy, from inception to completion, has had an uncredited co-author,” Alvin Toffler wrote in the preface. “It is the combined work of two minds, not just one, although I have done the actual writing and have accepted the plaudits and criticisms for both of us.”

“Whatever the faults of this trilogy,” he added, “they would have been far more serious without her skeptical intelligence, her intellectual insight, keen editorial sense, and general good judgment about ideas and people alike. She has contributed not merely to after-the-fact polishing but to the formulation of the underlying models on which the works are based. . . . I feel that the trilogy is as much hers as mine.”

The Tofflers offered few precise explanations for why credit was apportioned the way it was, with Alvin Toffler saying that Ms. Toffler declined to be listed on book jackets “out of integrity, modesty and love.” That changed beginning in 1993, when she was listed as a co-author on “War and Anti-War: Survival at the Dawn of the 21st Century,” the first of several books that featured both Tofflers on the cover.

“The idea of having a byline didn’t really do anything for me,” Ms. Toffler told the Times after it was published. But Alvin Toffler’s references to her in the acknowledgments section had grown “more effusive and more fulsome,” she continued, “and the feminist movement put a lot of pressure on me and said I was a very poor role model. And then men would come up and say, ‘We just wanted to tell you we think you have such a wonderful husband for giving you all that credit’ — implying that I wasn’t doing any work. That finally pushed me over the edge.”

By then, the Tofflers probably had become the world’s most influential futurists. Individually or as a duo, they met with President Ronald Reagan and Soviet leader Mikhail Gorbachev; spent three hours with Romanian strongman Nicolae Ceausescu; and became superstars in China, where “The Third Wave” was discussed at conferences organized by then-Premier Zhao Ziyang.

At the root of their work was a sweeping conception of human history that made them “a kind of cyber-age version of Marx,” author Barbara Ehrenreich wrote in a review for the Times.

The Tofflers traced human progress through three “waves,” transformations that occurred when hunting and gathering gave way to farming; cities ballooned under industrialization; and, most recently, when standardized mass production gave way to goods and services tailored for specific users.

In this “third wave” of development, they wrote, knowledge replaced “land, labor and capital” as the means of obtaining power and wealth, and governments and companies steadily became more decentralized.

Such views made them popular with conservative politicians such as then-House Speaker Newt Gingrich (R-Ga.), who returned them to prominence in the mid-1990s when he included their book “Creating a New Civilization” (1994) on a required-reading list for fellow representatives. The book later featured a foreword by Gingrich, whom the Tofflers described as a close friend, while eluding political categorization and insisting they were neither Republicans nor conservatives.

Ms. Toffler was born Adelaide Elizabeth Farrell in New York City on Aug. 1, 1929. Her mother was Dutch, and her father was a German American; they separated when she was 4, according to a profile in the Guardian. The Times reported that her mother worked for the telephone company and that her stepfather, who adopted her, worked for the subway system.

In 1949, she received a bachelor’s degree in English from Long Island University. She was doing graduate work in linguistics at New York University when she met Alvin Toffler and, in 1950, they moved to Cleveland, married and began working industrial jobs.

“I’d been reading Steinbeck,” Alvin Toffler later told The Washington Post. “I wanted to write the great American novel, and factories were going to be for me what lettuce was for him.” The experience also served as a kind of immersive research project, enabling them to test their Marxist theories on labor and industrial manufacturing.

While Alvin Toffler worked as a welder, Ms. Toffler made lightbulbs, then joined an aluminum foundry and was elected shop steward for the United Auto Workers. Her husband later became a journalist, eventually as a labor columnist for Fortune magazine. By the mid-1960s, they had begun work on “Future Shock.”

For decades, critics were divided on their work, which proved startlingly correct and, in several cases, far off the mark. They forecast the use of disposable paper clothes and predicted the rise of a Chinese leader known as “Mao II,” whose Christian fundamentalism would replace communist ideology.

And while their works were peppered with academic neologisms such as “prosumer,” “obsoledge,” “producivity” and “complexorama,” there were also ­flashes of wit. In one of their final works, “Revolutionary Wealth” (2006), they wrote: “Nowhere is a failure to achieve perfect synchronization more lamented than in the bedroom — unless it’s when the U.S. Federal Reserve or the Bank of Japan raises or lowers interest rates and gets the timing wrong.”

Ms. Toffler’s only child, Karen Toffler, died in 2000, and her husband died in 2016. She leaves no immediate survivors.

News reports often noted that while Ms. Toffler allowed her husband to steer interviews and take charge in public, she often emerged as the more outspoken personality when interviewed alone.

“It’s hard when we are together because Al wants to be liked more than I do,” she told the Times. “Al doesn’t feel as strongly about things as I. And maybe that’s one of the reasons why Al and I have such a good partnership. Somebody once said that when I’m talking, Al is listening very raptly — as if he’s hearing it for the first time. That’s because Al never knows what I’m going to say. I pretty much know what Al is going to say.”