Barbara Gladstone, an art dealer whose eye for spotting talent and knack for nurturing it helped her to build one of the largest and most influential contemporary art galleries in New York, died on Sunday in Paris. She was 89.

Her gallery said her death, in a hospital, was caused by an ischemic event, whose symptoms are similar to those of a stroke. Ms. Gladstone, who was on a working trip to Paris, lived in Manhattan.

Ms. Gladstone represented more than 70 artists and estates, including Americans like Robert Rauschenberg, Keith Haring and Elizabeth Murray; the provocative video and installation artist Matthew Barney; pivotal figures of the Italian Arte Povera movement like Mario Merz and Alighiero Boetti; Richard Prince, the pioneer of photographic appropriation; the diffident realist painter Robert Bechtle; the Iranian American filmmaker and photographer Shirin Neshat; and stars of more recent vintage like the sculptor Wangechi Mutu and the photographer LaToya Ruby Frazier.

What brought these disparate artists together on her list was her abiding interest in them personally and the devoted way she husbanded their work.

“At the core,” Mr. Barney said in a phone interview, “Barbara was a romantic.”

He recalled the trust she showed him when he was preparing their first show together, in 1991, which turbocharged both their careers. “We made a video within the gallery and ended up having to shoot through the night because we weren’t very organized,” Mr. Barney said. “Barbara gave me the keys and said, ‘Make sure you lock up when you leave.’”

In addition to occupying two large exhibition spaces in Manhattan, in the Chelsea arts district and on the Upper East Side, Ms. Gladstone’s gallery has opened branches in Brussels, Seoul and Los Angeles in recent years.

In 2020, as part of a deal that made the gallerist Gavin Brown a partner after his own operation had closed, she took on 10 of his artists, including Ms. Frazier and the painter Alex Katz, as well as the estate of Jannis Kounellis, another titan of Arte Povera.

By the standards of her mega-gallery peers, all this amounted to a fairly modest kind of expansion — but that was how she liked it.

“I think with a mega-gallery, there has to be such a division of labor that whoever’s gallery it is can’t possibly be talking to all of the artists. That’s impossible,” Ms. Gladstone said in a recent interview with the journalist Charlotte Burns. But she added: “I’m talking to the artists. That’s what I want to do.”

These conversations could go on for decades, she told The Wall Street Journal in 2011, comparing her practice of nurturing artists to raising a family. “Being a parent, a mother,” she said, “means that you’re responsible for helping someone develop to the best of their potential.”

The artists felt her attention. “It was a lovely thing,” the painter Carroll Dunham said by phone. “You felt incredibly supported and believed in, and felt you had this person out in the world working on your behalf.”

Though she denied having been driven by any longer-term vision than her own curiosity, Ms. Gladstone made plans for the gallery’s future in her absence. Max Falkenstein, its senior partner, took on an ownership position in 2016 and will continue to lead the operations in collaboration with his partners, Mr. Brown, Caroline Luce and Paula Tsai.

Ms. Gladstone was born Barbara Levitt on May 21, 1935, in Philadelphia to Evelyn (Elkins) Levitt and Joel Levitt. Her father manufactured children’s wear.

Two marriages, to Elliot Regen and Leonard Gladstone, ended in divorce.

Ms. Gladstone began her career in the 1970s as a collector with a limited budget. “If you couldn’t have a Frank Stella painting,” she told Ms. Burns, “you could have a Frank Stella print. Or you couldn’t have a Jasper Johns painting, you could have a print.”

At the time, she was raising three children in Roslyn, N.Y., on Long Island, and teaching art history at Hofstra University, where she had earned a master’s degree after dropping out of the University of Pennsylvania to marry. She sold some of her prints through classified ads in the back of an industry newsletter, but she had a restless hunger for broader horizons.

“At a certain moment I thought, ‘There have to be other artists, there just have to be,’” she said.

She sought out unrepresented artists who would leave slides of their work at young nonprofits like Artists Space or the Drawing Center, where dealers like Ms. Gladstone could look through them.

“So I would go and look and see artists who were unaffiliated and who just came to New York,” she said. “I would go visit them, become friendly with them, talk with them, eat with them.”

She opened, with a partner, what she called a “works-on-paper gallery” in 1979 on East 57th Street in Manhattan. Within a year the partnership broke up and Ms. Gladstone began expanding from prints to unique works while opening her own space, on West 57th. She later moved her gallery to SoHo, on Greene Street, in the thick of the neighborhood’s burgeoning art scene.

She is survived by her sons, Richard and David Regen; three grandchildren; and a sister, Joan Steinberg. Another son, Stuart Regen, died in 1998.

One secret to Ms. Gladstone’s success was her agility in changing direction. “Barbara is someone who really loves reinventing herself,” Mr. Falkenstein said in an interview on Tuesday.

Another was her talent for collaboration (that first fizzled partnership and other estrangements notwithstanding). Long before absorbing Mr. Brown’s gallery, Gavin Brown’s Enterprise, Ms. Gladstone ran spaces with the gallerists Rudolf Zwirner and Christian Stein. And in 1996 she made landfall in Chelsea by teaming up with Metro Pictures and the Matthew Marks Gallery to buy a 29,000-square-foot warehouse on West 24th Street.

The real secret, though, according to Barbara Jakobson, an art collector and longtime friend, was that Ms. Gladstone never stopped asking questions and always knew where to go for advice. On one occasion, as Ms. Gladstone recounted in her interview with Ms. Burns, the critical source was her husband at the time, Mr. Gladstone, a businessman.

“He said, ‘If you think every time you have to make a decision: What if it doesn’t work? What will I do then? Can I survive? If you can survive, then you do it,’” she recalled. “And I’ve just gone by that my whole life.”