There was much to spy on Saturday night in Brooklyn, where block after snow-covered block echoed with uproarious laughter, clanking glasses, and holiday music. And then the parties spilled out onto the street as more than 900 folks left the warmth of the home hearth for the bustle of the Heights Casino, a tennis and racquet club turned into a ballroom for late-night dancing and dessert.

To the veteran observer of Brooklyn society, it could mean only one thing: The Yuletide Ball had arrived – with more diversity, more style, and more youth than ever before. This 85-year-old fundraising event for the Brooklyn Kindergarten Society, which runs early education centers in three of the city’s poorest neighborhoods (Bedford-Stuyvesant, Crown Heights, and Brownsville), is booming, thanks to established and burgeoning support in the borough’s highest-income neighborhoods.

The bedrock of the event is strong: sit-down dinners for eight to 12 guests – mostly bankers and lawyers – in formal dining rooms of Brooklyn Heights brownstones. But added this year was Alison and Joshua Lindland’s dinner for their 20-something friends in their fourth-floor apartment on Schermerhorn Street, such as up and coming jazz record producer Chauncey Upson. At a Boerum Hill brownstone, Leslie Marshall and Mauro Premutico welcomed St. Ann’s parents, including the president of MTV, Christina Norman, to their loft-like brownstone, where the fireplace was so modern it didn’t have a mantel. And over in Park Slope, 50 Packer Collegiate parents dined elegantly in Tracy Brown and Joseph Kusnick’s contemporary townhouse, half a block from Prospect Park.

The Yuletide Ball’s new geography and the new sensibility are in line with the demographic shifts in the borough generally. Still, it’s remarkable for such an old-line event to transform so rapidly.

Several factors explain it. Ball newcomers talked about the greater sense of community they feel in Brooklyn, which makes them want to get involved.

Ms. Lindland has planned fund-raisers for a Manhattan-based theater company, but now that she’s married and a homeowner, her interests are changing.

“I thought it’d be nice to get involved with something local and neighborly,” Ms. Lindland, who bought her party dress on eBay, said. “And I am such a sucker for a party.”

“For me, it’s quite charming and delightful, to live in a small town with open minded people who have the means to do exciting things philanthropically,” Dr. Irwin Grosman, who works at Long Island College Hospital and attended the St. Ann’s dinner, said. “I’ve never felt as much a part of the community as I do now.”

Dr. Grosman and so many others were particularly enthusiastic about the Brooklyn Kindergarten Society, which provides preschool, day care, and after-school programs to 400 children.

“It’s such a tangible thing you can relate to, as a parent,” Dr. Grosman said.

“I’m a huge champion of early education and addressing educational inequities,” Valery Joseph, a children’s wear product developer who lives in Fort Greene and who doesn’t have children, said.

The format of the event exerts its own influence. Going to a dinner party in someone’s home is more enticing than sitting in a hotel ballroom for a charity fund-raiser. And when a friend has invited you, you have some guarantee of a crowd you’d like.

“The event is really about the dinner. It’s not about exclusivity. It’s about familiarity,” a first-time guest from Manhattan who works in the hotel business, Erin Green, said. “Once you’ve had time in your comfort zone, then you can go off into a party this size,” pointing to the multigenerational crowd on the dance floor at the Heights Casino.

Having generous couples provide – and pay for – dinners in their home results in a reasonable ticket price for a charity event: $150 (“angels” pay $550). The Brooklyn Kindergarten Society’s costs are modest: about $35,000 for printing and mailing invitations and putting on the dance party. The organizers are impeccably frugal, even saving their decorations for use from year to year.

“This is the real thing. They have more expensive ways to do this across the river,” a private equity and venture capital executive, Roman Kyzyk, who attended the dinner at Theodore Bajo and Gloria Lanza-Bajo’s home, said.

This year, the society’s enterprising committee arranged for all of the expenses to be covered by corporate underwriters such as Commerce Bank and Independence Community Bank. That meant 100% of ticket proceeds – $190,000 – went straight to the organization.

agordon@nysun.com