"It may not have been the perfect time economically," he conceded, "but personally, it suited me."

A little more than three years later, after a spate of critically acclaimed, popular exhibitions that boasted new stars and contemporary art legends like Bill Viola, Robert Smithson and Richard Long, Mr. Cohan has emerged in a fresh 6,000-square-foot space as Chelsea's newest art heavyweight, with clients ranging from Hollywood celebrities to national museums.

"People take Jim's call," said Michael Auping, chief curator of the new $65 million Tadao Ando–designed Modern Art Museum of Fort Worth. Mr. Auping added that Mr. Cohan's "easygoing" and "casual" approach to selling art has made him many friends in a milieu known for its prickly backroom skirmishes. His squeaky-clean reputation and provenance hasn't hurt, either.

Before launching his own gallery, the 43-year-old Mr. Cohan worked for some of the most important names in the contemporary art world, including Paula Cooper, John Weber and, most recently, the British dealer Anthony d'Offay. The latter's roster of artists (he closed his galleries in 2001) read like a Who's Who of contemporary and modern art: Jasper Johns, Andy Warhol, Roy Lichtenstein, Sigmar Polke, Gerhard Richter, Anselm Kiefer, Jeff Koons and Rachel Whiteread, to name a few. Mr. Cohan, as one of Mr. d'Offay's senior directors, was soon handling their work.

There was little glamour evident, however, on West 26th Street near Mr. Cohan's new gallery early on a recent cold, gray weekend morning in January. The block of warehouses was lined with rental trucks, the irregular, sloped sidewalks were deserted, and most of the businesses and galleries were still shuttered. The last two years have not been easy on the art world, and a number of important galleries have been struggling for survival. On that morning, it turned out, the only other two people on the block were also going to the James Cohan gallery. The brocade of shimmering, silvery-blue sequins draped outside the gallery walls-a Howard Goldkrand allusion to the subject of the exhibition inside, but not unlike those strings of tinsel that attract business to a car lot-signaled that the gallery was definitely open for business. Two little white speakers on either side of the entrance transmitted the thin, robotic voice of the Marine Weather Center and the 10th Precinct police station. It's a familiar voice to fisherman heading out to sea-less well-known, perhaps, to art-loving Manhattan pedestrians who seemed only subconsciously to hear its dire forecast of more icy weather and bitter breezes from the north.

The theme and title of Mr. Cohan's current exhibit is Air . The announcement card is a simple, inviting photograph of a baby-blue sky with only a trace of cumulus clouds in the bottom corner. Down the middle, written in a faint white print, are the names of over 30 formidable artists ranging from John Constable (yes, the 19th-century British painter) to Damien Hirst.

"The idea [for the gallery] is to meld a variety of influences, and bring together ideas about nature and culture," Mr. Cohan said, his legs crossed, leaning back in a chair to the side of his desk. On a more practical level, he said, the gallery is about doing away with pretensions and making contemporary art accessible to the public. Tall and thin, Mr. Cohan has a handsome, narrow face and short, cropped, curly black hair speckled with gray. His clothes are tidy, but casual-in fact, there's little of the slick art-dealer stereotype in Mr. Cohan, who is married with two children and lives in Park Slope. At openings, he sometimes wears brightly colored bow ties and, with his steel-rimmed glasses, looks more the nerdy professor than suave art-world savant.

"I want people to enjoy themselves when they are here," he said.

Over the past three years, he has demonstrated a flair for presenting off-beat, curiously titled theme exhibitions that combine serious, established avant-garde artists of the past with attention-getting newer artists like Roxy Paine who, as many newspapers noted last year, installed a 50-foot stainless steel tree in Central Park. Likewise, the current exhibit shows a veritable panoply of artists, including 19th-century painters like Turner and Courbet, as well as conceptual modernists from Marcel Duchamp to Robert Gober and Jeff Koons. But a reclusive young Texan artist named Erick Swenson is responsible for the most striking sculpture in the exhibit-a kind of miniature white deer balanced on one hoof as a black and scarlet cloak, seemingly ripped from Zorro's back, threatens to carry the dainty animal into the sky.

At other previous performance/exhibits, Margaret Leng Tan, a master toy pianist, played John Cage and Beethoven on a Schroeder-sized keyboard. Lee Renaldo of the group Sonic Youth performed a tribute to Robert Smithson (the gallery handles his estate), and Maggie Estep read from her novel, Soft Maniacs . Last fall, the gallery showed Harry Smith, eccentric ethnic musicologist, experimental filmmaker and darling of the bohemian art world. In fact, much of the art-whatever the medium- that's shown is not necessarily for sale.

What's drawn people to the gallery, said Gary Garrels, the chief curator of drawing and curator of painting and sculpture at the Museum of Modern Art, is the "inventiveness, intelligence and freshness" of the exhibits. Some of this razzle-dazzle-though Mr. Garrels wouldn't characterize it as such-is attention-getting. Some of it is Mr. Cohan and his team's intention to create a kind of Kunsthalle cultural center out of the gallery. And still another part of this eclectic approach can be attributed to Mr. Cohan's care not to take himself too seriously.

"I walked in here last night," he said on the evening of the Air opening, with guests milling all about, "and I thought, 'This is crazy-no curator in his right mind would put on an exhibit like this.'" Then he let out a characteristic disarming chuckle.

Mr. Cohan and the gallery's directors-Elyse Goldberg and Mr. Cohan's cousin, Arthur Solway-emphasized the collaborative effort involved in finding the artists, curating the shows and, of course, selling the work. "We work together as a family" said Ms. Goldberg. Mr. Cohan's wife, Jane, is also part of the organization.

It was cousin Arthur's father, Carl, who first introduced Mr. Cohan to the business of showing and selling art when he drove up to the Cohan family house in Cleveland in 1971 in a VW van filled with modern art. James Cohan, age 11, watched slack-jawed-his own father was in the appliance business-as his uncle unloaded a Miró scroll and a Noguchi sculpture from the van, set up an exhibition in the house and sold the art to their neighbors. The young Cohan later spent a spring break with his uncle in Cincinnati boning up, and by the time he was a senior in high school had finagled an internship at the New Museum in New York working with Marsha Tucker. After graduating from Washington University in St. Louis, Mr. Cohan returned to New York and eventually went to work for the John Weber Gallery. By the late 1980's, he was director of the Paula Cooper Gallery in Soho.

"He was charming, twinkle-eyed and he loved to sell art," Ms. Cooper said.

Mr. Cohan is somewhat reluctant to talk about money, but admits to his talent for selling.

"I love to watch someone become engaged to an idea and become attached to an object," he said. "It's wonderful."

At the d'Offay gallery in London, where Mr. Cohan went to work in 1991, he was a big part of the $35 million in sales generated a year. Not only was he good with dealers and curators, he also had a way with artists. Over dinner one night, Mr. d'Offay asked Mr. Cohan what one artist he would want to add to the gallery's list. He picked Bill Viola, an artist whose work he had been following for several years. He tried to set up a meeting. Mr. Viola was on his way to becoming the most important video artist of his generation (the Whitney Museum of American Art held a retrospective of his work in 1998) and had, a few years before, sold his first important piece for a lot of money to the Museum of Contemporary Art in Los Angeles. Mr. Viola (whose new show, The Passions , just opened to great fanfare at the Getty Museum in Los Angeles) remembers the quandary he faced at that time.

"It was like dipping raw meat into the Arauca River," Mr. Viola said, describing the effect of his sudden financial success on the art world. "The piranhas started to appear out of nowhere."

Everywhere he went, Mr. Viola said, he heard stories from other artists about getting burned and ripped off by dealers. It took some time, but he and Mr. Cohen finally met up at an exhibit in Nantes, France, in 1992.

"We immediately connected in a very real way," Mr. Viola said, "and I felt very comfortable with him. He's a very honest and straightforward guy."

Roxy Paine echoed Mr. Viola's sentiments. His elaborate projects often take a considerable amount of planning. In the case of the tree he made for Central Park, Mr. Cohan convinced the Public Art Fund and, ultimately, the Whitney Museum to help provide the support necessary to complete the project.

"Whatever is needed to make a project happen, Jim will come up with that," Mr. Paine said. "He makes it happen."

Mr. Cohan's breakup with Mr. d'Offay, which could not have happened at a more challenging moment in Mr. Cohan's career, ended without the legal battles and backstabbing that often accompany such events in the art world.

"We worked together for eight or nine years, so like any kind of partnership, it had its bumps, but ultimately it was fine," Mr. Cohan said.

It was in 2000, when Mr. Cohan was running a private dealership for Mr. d'Offay in New York out of his Philip Johnson townhouse on 52nd Street, that he finally decided to go out on his own and found a gallery. He opened it uptown, on a small scale, to give him time to set up shop and get settled out of the limelight. Mr. d'Offay helped him get started, but shortly afterward pulled out of the partnership. By then, however, Mr. Cohan's gallery had put on several well-received exhibitions, and his artists included Mr. Viola, Mr. Paine, the estate of Robert Smithson, Fred Tomaselli, Ron Mueck and Richard Patterson.

"We felt we were in a good position to expand," Mr. Cohan said. "There was a momentum that we were building, and we wanted to take advantage of that." From the looks of it, the Cohan gallery is still moving forward.

By the time I left the gallery that January morning, the vast open spaces were filling up. There were well-attired couples from Europe, artists in dirty black jeans, a museum director from North Carolina. Looking about the room at the objects and paintings, one began to appreciate the simple art of Mr. Cohan's success.

"Art is a portal to another reality," Mr. Cohan had said earlier, discussing his client Fred Tomaselli's paintings. "But ultimately, notions of utopia are unattainable."

Perhaps, but in Air -where he has mingled Garry Winogrand's famous picture of Marilyn Monroe's upturned skirt, a melancholy seascape by J.M.W. Turner and a whimsical, floating blue chiffon installation by Hans Haacke-as well as in his other eclectic exhibits, Mr. Cohan has provided new thematic contexts in which to view (and hopefully understand) contemporary art.

True enough, Mr. Zabar, the renegade scion of the famous West Side Zabar family, has energetically created one successful business after another. First there was E.A.T. (where it's been said that biting your nails costs $10) on upper Madison Avenue, then there was the wholesale bakery Eli's Bread. Now Prada-toting gourmands regularly pack in to buy everything from pubescent veggies to aged Gruyère at his gourmet food warehouse, the Vinegar Factory.

But Mr. Zabar's latest idea, a greenhouse on the roof of the Vinegar Factory, has some of his most loyal customers angrily crimping their appetites. There's a small problem in epicurean paradise: Mr. Zabar's expensive rooftop-garden vegetables–some labeled as "organic"–are grown in raised beds boxed with wood that has been soaked in arsenic, chromium and copper, commonly known as pressure-treated wood. Ted Cancalosi, a jeweler who works in the area and regularly shops at the store, is worried. "I won't buy any of his produce unless I'm assured it hasn't been grown on the roof," he said.

Mr. Cancalosi isn't the only one who's concerned. When The Observer made a routine inquiry to the New York State Department of Agriculture and Markets, spokesman Pete Gregg said the use of pressure-treated wood in commercial vegetable gardens would raise a red flag. "We would have a problem with that," he said. "We object to the practice [of using pressure-treated wood], and if after testing we find that a product has been adulterated by this practice, we shall seize the product and take it off sale." Mr. Gregg said the extensive watering used in large commercial beds would increase the chances of low-level contamination from the treated wood. "The vegetables would absorb the chemicals like sponges," he said.

The potential harmful effects of pressure-treated wood have been widely debated. Organic farmers generally shun the product because the preservative chemicals (chromated copper arsenicals or C.C.A.) leach into surrounding soil (just how much leaches depends on which study one reads). "Pressure-treated wood is prohibited from being used in garden beds on our certified organic farms," said Pat Kane, who is the administrator of certification at the Northeast Organic Farming Association of New York. Breathing sawdust or smoke from the wood has serious consequences. Direct ingestion of wood particles can … well, two quarter horses reportedly got sick and died after gnawing on a pressure-treated fence in Florida.

However, lumber-industry experts maintain that the wood is safe and the amount of leaching is nontoxic. The Environmental Protection Agency says that pressure-treated wood does not pose "unreasonable risks" or "significant health concerns" (as long as workers wear chemically impervious gloves, long-sleeved shirts and pants when handling the wood, and wash sawdust-contaminated clothes separately). But this has not assuaged worried shoppers. Their reaction echoes the concern of millions of parents who watched a Hard Copy exposé last year on the dangers of C.C.A.-treated wood in children's playgrounds.

"We were horrified," said Mr. Cancalosi whose office has a bird's-eye view of the Vinegar Factory's roof garden. On a recent afternoon, Mr. Cancalosi and a fellow office mate looked across at the incomplete greenhouse. Stacks of greenish treated lumber lay on the roof; newly constructed beds had been filled with soil; tiny green leaves poked through the dark dirt. "It's obviously pressure-treated wood," he said. "We saw him building the beds with it. Then we saw him putting the dirt directly into it." Mr. Cancalosi and his friend shook their heads in dismay. "And he likes to brag about his organic garden!" Down below on the busy street, nearly two dozen delivery trucks and vans were idling or parked, and in the space of a few minutes, three city buses and two sanitation trucks roared by, spewing dark exhaust fumes into the air.

Zabar 'Brought in Ladybugs'

"I'm not making any claim that it's organic," Mr. Zabar repeated a half-dozen times in between bites on his cell phone. But as of June 16, when a reporter visited the store, a tangy mountain of exotic mesclun was clearly marked as being baby organic salad harvested from the rooftop greenhouse. Propped above the sign was a three-foot-tall color photograph of Mr. Zabar himself, the proud "urban farmer," with his arm draped around his produce manager's shoulder. Just about every bin in the area is marked organic. Down the aisle, Mr. Zabar sells the Northeast Organic Farming Association's guide and recipe books, which the Vinegar Factory newsletter reviewed: "Organic farming can only benefit from our increasing awareness of the dangers of chemical insecticides and our desire to raise healthy children." Mr. Zabar has made a big deal in his market newsletter about the fraises des bois that were grown in the greenhouse. An article about the garden, and a photograph of Mr. Zabar's twin sons gardening in the greenhouse, have appeared in The New York Times .

"My goal is to grow things in a healthy way," Mr. Zabar said. He said all the soil used in the roof garden was imported from McEnroe Organic Farm in Millerton, N.Y. He stressed that no chemicals or sprays have been used. "When we had aphids, we brought in ladybugs."

But Mr. Cancalosi and some other neighborhood shoppers said they aren't buying it. They've restricted their purchases at the Vinegar Factory, not just out of concern about their health, but also because they're angry at being duped.

"I object to being lied to and being taken for a ride," said one customer whom we'll call Sally (she asked that her real name not be used). "I'm a concerned shopper. I want to buy what's clean and good." Sally said she pays the extra price for healthy organic food. "But I want it to be what it's advertised as. This is not clean, healthy food." Sally, who admitted she still buys Eli's Bread, did some research about pressure-treated wood and complained in April to store managers about the rooftop boxes. The manager said he would pass along the information to his boss. Indeed, the organic signs subsequently vanished for a few weeks, but then reappeared. "I'm not certain what the sign in the store says. I'll have to go take a look at it," said Mr. Zabar, who is known to be a brusque perfectionist about every detail in his stores. "Any signs in the store that are misleading will be changed immediately."

That doesn't soothe everyone's fears. "I think the use of pressure-treated wood for raised garden beds is alarming," said Senga Mortimer, gardening editor at House & Garden magazine. "These chemicals are usually toxic and can be absorbed by any plants," whether those plants are organic or not.

If shoppers can't believe what Mr. Zabar says about his own vegetables, some patrons muse, how can they be sure about the baby carrots and cucumber in the neighboring bins that are labeled as being from someone else's organic farm? It's a problem for any shopper in any food store in New York State because there are no laws in New York that govern what is considered organic.

Mr. Gregg of the Agriculture Department said, "You can slap an organic label on a Twinkie, and no one can say you can't." The department, Mr. Gregg explained, used to test organic foods around the state for pesticides. "We were finding high levels of pesticide residue on 'organic' fruits, but because there is no law, we couldn't take any action against these people who were fraudulently presenting their products to consumers. It's a self-regulating industry, and there are going to be some bad apples." In fact, Mr. Gregg warned, organic fruits and vegetables may be less safe to eat than regular produce because they are unregulated.

Because of these problems, the booming organic-farming business community is trying to come up with regulations and standards to ensure that high-priced vegetables sold as organic are true to their label. Currently, only about 13 states have laws or regulations governing organic food. The National Organic Standards, or N.O.S., proposed by the U.S. Department of Agriculture have been scorned by organic organizations, which claim the N.O.S. has loopholes wide enough for a tanker trailer of insecticides to drive through. While the original N.O.S. was split on the use of pressure-treated wood, the revised version some experts think will take a tougher stand. "My feeling is the revised proposal will prohibit the use of pressure-treated wood in organic farming," said Cheryl Long, research editor of Organic Gardening magazine. A revised N.O.S. is in the works, but it may take years to be agreed on.

On his portable phone, Mr. Zabar pedaled back and forth between talking about how everything in his greenhouse is organic and healthy, and saying he is not claiming that the products are organic. (Subsequent to the conversation, signs in the store were changed to say the vegetables are grown in "a healthy environment.") Before he hung up, though, Mr. Zabar took a firmer stance. "I'm going to address these concerns," he said. Then he promised, "For reasons other than organic, we're going to be lining all the beds in plastic for our winter production."