This year’s more than 3,000 attendees arrived in groups led by volunteers—as per tradition, the location of the dinner is kept a secret from the diners until that evening, to preserve at least an illusion of spontaneity. The rules for participants are strict: they must carry in their own table, chairs, white tablecloths, flatware and four-course dinners, and they must dress entirely in white. “This means no ivory, no cream or any other color will be permitted,” a discussion thread on the event’s website from one of the hosts stated, advising attendees to dress “elegantly.” Elizabeth Hill, an elementary school teacher, even wore her wedding dress.

“Well, it’s white, and it’s all I had!” she said, explaining that she and her husband had decided to come at the last minute when their friends offered them tickets. “Might as well,” she shrugged.

Luckily for everyone in attendance, there was no sign of rain, though a few diners showed up with white umbrellas, just in case. The dinner is held rain or shine, and no-shows who balk at a cloudy sky are not invited back. And, with last year’s waiting list topping 30,000, invitations are hard to come by.

“The best option to get invited is to know someone who is a member of Dîner en Blanc” explained Aymeric Pasquier, the son of François and one of the chief organizers of the New York event. Once diners attend one dinner, they become members, and each member can invite one guest to the next dinner. The waiting list this year was around 5,000 (“It went to a normal standard to interest,” Mr. Pasquier said, laughing), and priority went to those who didn’t make it off the waiting list for last year’s dinner, which boasted 1,200 attendees at the World Financial Center.

Mr. Pasquier said he was keen to have this year’s event at Lincoln Center because of Dîner en Blanc’s efforts at international development—the viral culinary event has spread to eight additional U.S. cities this summer, and now spans five continents and 22 cities. “The Metropolitan Opera is famous all over the world, and we wanted the best spot in New York,” he said. “And we are basically in the best location in New York for this kind of event. It fits perfectly for the Dîner en Blanc.”

Though many in attendance shared Mr. Pasquier’s sentiments regarding the surprise location, a few were less impressed. “I think they could have done better,” said Matt Hill, a software developer. “I thought it was going to be in Central Park. For a picnic, it would be nice if it were green, rather than in a square known for its fascist architecture.”

“I was hoping it would be in Brooklyn Bridge Park, since I just went there a week ago and it’s awesome,” said Colin Hoffman, a traffic designer whose general enthusiasm was fairly representative of the event’s demographic. “But this is cool too,” he conceded easily.

Indeed, the diners seemed unreservedly interested in maintaining the evening’s elegance despite the evening’s questionable soundtrack (when we headed out, The Wanted’s “Glad You Came” was blaring). Though we heard some grumbling from guests who had to wait an hour for the wine they had reserved.

When asked whether he had any concerns about controlling such a large crowd (police barricaded the plaza, ostensibly to keep those not following the dress code outside the fenced-off area), Mr. Pasquier responded very firmly that he did not. “Everyone is respectful of what Dîner en Blanc is,” he explained. “They all know the history of the event and the philosophy of the concept.”