Ileana Sonnabend

Ileana Schapira, art dealer and gallerist: born Bucharest, Romania 28 October 1914; married 1933 Leo Castelli (one daughter; marriage dissolved 1959), 1960 Michael Sonnabend (died 2001; one adopted son); died New York 21 October 2007.

In the last interview he gave before his death in 1987, Andy Warhol was asked to comment on a remark – "For Andy, everything is equal" – made about him by the gallerist Ileana Sonnabend. Warhol thought about it for a second and then said, "She's right." Challenged by the interviewer to expand on his answer, a clearly rattled artist snapped, "I can't. If Ileana said it, she's right." Even for Warhol, there was no arguing with the woman known as "the mom of Pop".

This was reasonable enough. Sonnabend's status as the unquestioned queen of the SoHo art world had been won over half a century, two marriages, a pair of continents and just about every artist of note since Jasper Johns. Sonnabend was the woman who took Warhol to Europe in a ground-breaking exhibition called "Pop Art Américaine" at her Paris gallery in January 1964. Warhol had had his first solo show in New York just over a year before; while Sonnabend alerted the French to his existence, he was busy opening his first Factory at 231 East 47th Street. Pairing him with more established artists such as James Rosenquist and Lee Bontecou took not just courage but a degree of imperiousness.

Sonnabend had never lacked for either. Born in Bucharest into the lost world of well-heeled Mitteleuropa Jewry, Ileana Schapira was only 17 when she met her Triestine first husband, the great gallerist-to-be Leo Castelli. Insisting on a Matisse rather than a ring to mark their engagement, she married him the following year. Ileana's immensely rich father set his new son-in-law up in banking, arranging his transfer to Paris, at Ileana's behest, in 1935. Moving in Surrealist circles, Castelli eventually gave up the bank and, drawing on his wife's flair for art, opened a gallery in the Place Vendôme in early 1939. It was a rare example of bad timing. Within months, war had broken out and the couple moved to join Ileana's parents who had fled to New York.

The refugees arrived in typical style, with a long-haired dachshund and their daughter's English nanny in tow. Although Leo served in the US Army and then, for the next 15 years, worked in manufacturing, the Castellis continued to move in such artistic circles as New York had to offer. Through Peggy Guggenheim, they met Marcel Duchamp and Jackson Pollock; in 1950, the couple curated a show of young American and European painters which included both Jean Dubuffet and Mark Rothko. In 1957, the Castellis opened their first Manhattan gallery in their drawing room at East 77th Street, showing the work of artists such as Jasper Johns and Robert Rauschenberg.

Although their business thrived in the United States, their marriage did not. Castelli was a notorious womaniser. When he began an affair with a French au pair girl he had met on the beach near their weekend house in East Hampton, his wife finally left him. In 1959, they were divorced; the following year, Ileana married Michael Sonnabend – typically, she proposed to him – and the pair set off for Paris.

Where Castelli had been worldly, Sonnabend, a Polish-born Dante scholar, was bookish and mild. According to their adopted son, Antonio Homem, "it was Michael who took the initiative and Ileana who acted on it". This may explain the kind of art, avant-garde but hard to sell, in which the Galerie Ileana Sonnabend tended to deal. Although the Sonnabends' name became synonymous with rigorous, cutting-edge work, its links with financial success were more tenuous. In 1968, the couple closed the Paris showroom and moved back to New York. In September 1971, Ileana Sonnabend opened her now fabled SoHo gallery in an old paper factory at 420 Broadway.

Once again, her move south of Houston Street proved prescient – within a couple of years (and largely thanks to the presence of the Sonnabend Gallery), SoHo had become the centre of Manhattan's burgeoning art scene. This time, though, Sonnabend's foresight also paid off financially. Where her first gallery had brought American art, uneconomically, to Europe, the second reversed the flow: the new gallery opened with one of Gilbert & George's Singing Sculptures, in which the bronze-painted British pair crooned "Underneath the Arches" to an audience of mesmerised New Yorkers. Artists like Mario Merz and Jannis Kounellis soon followed.

Perhaps Sonnabend's greatest quality as a gallerist was her genuine enthusiasm for the next big thing. Rather than resting on her laurels as the mom of Pop, she was among the earliest dealers to spot the promise of new movements, from Process Art to neoconceptualism. And her eye was more than just shrewd, it was passionate. In the 1980s and 1990s, the Sonnabend Gallery was the first to show the work of artists still regarded as challenging today.

Through all of this, Sonnabend herself remained an enigma. Tiny, plump and sporting an unconvincing wig, her reticence was legendary. This extended to her philandering first husband, with whom she remained both friendly and on good business terms. Asked by reporters for her views on the 88-year-old Castelli's last marriage, to a woman 50 years his junior, Sonnabend discreetly answered, "I have many thoughts, but no statement."

In spite (or perhaps because) of this, she inspired fierce loyalty in the artists she represented. Rauschenberg once remarked that he "never finished a painting without wondering what Ileana would make of it"; Jeff Koons recalled that Sonnabend was the only person, apart from his father, who felt she had the right to warn him against marrying the Italian porn star La Cicciolina.

This had nothing to do with prudishness, Sonnabend's views on sexual morality having been shaped in the liberal milieu of Thirties Paris. When the performance artist Vito Acconci announced that his Seedbed piece called for him to masturbate in her gallery for two weeks in 1972, Sonnabend simply replied, "You do what you have to do." This sang-froid, too, was part of her success. Explaining why he chose Sonnabend as his gallerist over the more established Mary Boone, Ashley Bickerton tersely said, "I asked myself one question: five years down the line, if I want to shit in the corner of the gallery, put up a plaque, and call it a show, who out of Mary and Ileana would let me do it?"

Charles Darwent