The lustrous gallery Thomas Segal opened on Newbury Street in 1976 was an elegant venue “where one approaches the plate glass entry up five tiers of discreetly carpeted steps,’’ Globe art critic Robert Taylor wrote. The experience gave visitors “the sense that somehow one has made a grand entrance.’’

That was only fitting because by launching the gallery, Mr. Segal had made his own grand entrance. In short order he became a significant force in Boston’s art world, using his connections in New York City to bring the work of major artists to the Back Bay.

The first Jasper Johns one-man show in Boston was staged at the gallery in 1981 after four years of planning — “an undertaking we usually associate with a museum,’’ Taylor wrote at the time, adding that “this is a subtle and powerful solo which fills in a blank on the map of Boston’s art scene.’’

For Mr. Segal, such exhibitions were part of his efforts to elevate the status of the visual arts in Boston. “I want the best I can get, no matter what,’’ he told the Globe in 1977. “And if this means going to New York to get it, I will.’’

An art dealer who combined refined tastes and a sharp business background, Mr. Segal died in his sleep Oct. 9 in his home in Baltimore, where he moved his business after about two decades in Boston. He was 77 and had been diagnosed with Parkinson’s disease.

Though he didn’t hesitate to travel to and from New York, where he had grown up, to search for fascinating art and artists, he cautioned in 1977 that “this doesn’t mean we’re a New York rehash. We’re going to be very aggressive in finding new talent. Only it should represent quality.’’

In 1983, he told the Globe that early successes at the gallery allowed him to take chances on exhibitions featuring younger artists. “Our current show is a good example of that policy, Ralph Hamilton, one of the most talented younger Boston painters, combined with the photographer Harry Callahan, who has an international reputation,’’ he said.

The gallery’s shows drew critical praise, which in turn established Mr. Segal’s own reputation far beyond Boston. Year after year, he introduced local collectors to art they might not otherwise have seen.

“Tommy was hard-wired into the New York art scene and had a keen eye for what was considered avant-garde. And he brought that to Boston and showed people with an interest in art how that could be accessible to them,’’ said Adam Sheffer, an art dealer based in New York who is president of the Art Dealers Association of America, an organization to which Mr. Segal belonged.

Sheffer added that Mr. Segal “was part professorial and part commercial, and I think that’s what made him so special. He really was a teacher to many of us, and he was unfailingly loyal to his artists, his collectors, and his friends. That’s a wonderful asset, regardless of what industry you’re in.’’

Mr. Segal also strongly supported the local art community and welcomed competitors. “The more galleries active, the better it is for the total scene,’’ he said in 1977. “If people think of finding good art in Boston, we’ll all benefit.’’

He was equally outspoken about the debilitating impact of Newbury Street’s rising rents, and for a time he moved his business elsewhere in the city. At a certain point, “you’re working for the landlord rather than yourself,’’ he told the Globe in 1983, as he compared Boston’s trendy shopping destination to an artsy New York neighborhood that had experienced similar rent upheaval. Galleries established Newbury Street’s ambience, Mr. Segal said, “but what’s happening is similar to SoHo — the landlords are driving out art.’’

One of three brothers, Thomas Hirsch Segal was born in Brooklyn, N.Y., where he grew up in the Bedford-Stuyvesant neighborhood. His father, Rabbi Samuel Segal, was a musician, artist, and writer. His mother, the former Cynthia Shapiro, was a homemaker.

Mr. Segal was a teenager when his family moved to Manhattan’s Upper West Side. He graduated from New Lincoln School and was a member of the all-city soccer team.

After receiving a bachelor’s degree from the University of Pennsylvania, Mr. Segal considered a medical career and attended the Boston University School of Medicine for a year before deciding that wasn’t his calling. Though his time there was brief, “he claimed that with his year he had learned everything,’’ said his daughter, Jennifer Herman of Wellesley. “He became the expert when anything was going awry with anybody — ‘Well, what I learned at medical school . . . ’’

Mr. Segal graduated with a master’s of business administration from Columbia Business School in New York and for a time worked in the Kay Windsor clothing business for his then father-in-law, Carl Shapiro.

With his first wife, the former Ronny Shapiro, Mr. Segal launched the Thomas Segal Gallery. He coined the slogan “buy art now,’’ which he used as a stamp on business correspondence.

At their Wellesley home, Mr. Segal and his wife often held parties to celebrate artists featured in their gallery. Some evenings, Mr. Segal’s older brother, Erich Segal, who wrote the bestselling novel “Love Story,’’ would stop by for dinner during long-distance runs from Cambridge, when Erich was teaching at Harvard.

Mr. Segal’s first marriage ended in an amicable divorce. His former wife, Ronny Zinner, died in 2014. His brother Erich died in 2010.

“My dad was always an extremely positive person. The glass was always half-full for him,’’ his daughter said. “He always had a great outlook on life, no matter what. If something didn’t work one way, he’d find a way to make it work.’’

Mr. Segal “was passionate about living,’’ said his son, Jonathan of Los Angeles. “He was passionate about people, about food, about art’’ — and languages, too. Along with English, Mr. Segal spoke Hebrew, French, Italian, Spanish, and a little Japanese. “Wherever he went, he loved talking with people in their native tongue,’’ his son recalled.

In the mid-1990s, Mr. Segal married Clair Zamoiski and relocated to Baltimore, where he continued to run his art business.

Private services were held for Mr. Segal, who in addition to his wife, daughter, and son leaves his mother, Cynthia Segal Zeger, and his brother, David, both of New York City; and three grandchildren.

“Tommy inspired me. He showed me that you can be perfectly serious about business and have a wonderful time as well,’’ said Sheffer, who grew up in Wellesley and first learned about art as a boy when Mr. Segal let him spend time in his gallery.

When Mr. Segal was with clients, “he was phenomenally articulate. He was never trying to sell you something. Rather, he was trying to teach you something. The selling came along as a byproduct,’’ Sheffer said.

“He would spend hours with people showing them who he believed were important artists,’’ Sheffer added. “And he was funny. I never had a conversation with Tommy that I didn’t learn something and I didn’t laugh. Nice guys don’t finish last — that’s what Tommy taught me.’’

Bryan Marquard can be reached at bryan.marquard@globe.com.