From a photograph of the Picasso painting “Les Demoiselles d’Avignon,” she learned art was her calling. From the teenage years she spent in Michigan she learned she was not in the place to do this. From the Rhode Island School of Design, she learned New York couldn’t come soon enough, and from a teacher at Hunter College, she learned that while her art was “terrible,” she might make a better dealer.

The professor who introduced this idea is Lynda Benglis, whose boyfriend in 1971 was Klaus Kertess. He ran Bykert Gallery, an influential but not especially profitable place on East 81st Street. Brice Marden and Chuck Close were among those whose paintings weren’t selling.

Ms. Boone began there as a secretary but had opportunities to do other things. That was an advantage that came from working at a place with limited resources and a boss who was figuring out he was gay. He needed space. She got responsibility.

Every afternoon, the gallery filled up with artists and collectors. Even among them, she stood out. “What I remember is this rivetingly beautiful dark-haired creature beavering away in her cubbyhole,” said Barbara Jakobson, a longtime Museum of Modern Art trustee. “You had this impression from the beginning that she was so in control in a way, that Klaus had come to depend upon her. She had this air of authority, an aura around her, even then.” (Ms. Boone said: “That is so not true. I was a nitwit. I didn’t know anything.”)

Around 1972, Ross Bleckner, who went to the California Institute of the Arts, walked into Bykert with a bunch of his slides. The paintings were dark and caustic, but he had a knack for social networking dating back to his childhood in the Five Towns of Long Island, where one of his best friends was Donna Karan. He introduced Ms. Boone to classmates of his like David Salle and Mr. Fischl, as well as his good friend Barbara Kruger.

After Mr. Kertess left the gallery, in 1975, Ms. Boone headed to SoHo and found a small ground-floor space at 420 West Broadway beneath the gallery of Leo Castelli, whose status as the most august dealer of contemporary art in the world was somewhat in decline.