In a couple of weeks, swarms of swells dressed elegantly in summery white — clad in fascinators, gowns, top hats, and tuxedos — will gather in Boston to trek to an unknown location for a gourmet picnic.

This is Dîner en Blanc, an international phenomenon launched in Paris in 1988 by François Pasquier. Pasquier, fresh from a trip abroad, threw himself a lavish welcome-home potluck, where each guest would bring a dish and a new friend. The guest list ballooned, so he asked his pals to rendezvous in a public park and to dress in all white. (How else would they recognize one another?) His guest list was 200, and the party was a smash. Now, the French version attracts 10,000 people each year, and similar events exist in 25 countries worldwide.

Boston’s Dîner en Blanc will happen on Saturday, July 30. Roughly 2,000 registered guests receive a tip-off on a meeting spot; a table leader then whisks them to a scenic mystery location for an opulent picnic. Guests provide their own folding table and white chairs, white picnic basket, white napkins, and tableware.

While the location remains a mystery until the last moment, one thing is certain: Everyone will be in white, no exceptions. According to published rules, “All guests must dress elegantly in head-to-toe white. This means no ivory, no off-white, and no beige,’’ to honor Pasquier’s vision.

The $37 per person feast attracts all ages, says Bryer Davis, a co-host. Last year’s event drew 1,500 people to?City Hall Plaza, despite rain.

“It’s really diverse. I see ladies in their 70s with this giddy-up, genuinely happy to be there,’’ she says.

Originality is encouraged. And therein lies the fun, especially in Boston, a city that can be reticent when it comes to fashion risks. Organizers say that guests enjoy pushing their sartorial limits with DIY fascinators, sequins, and feathers.

Some women repurpose their wedding dresses; others design towering hats. Roxbury’s Tamy-Fee Meneide, a table leader at Boston’s soiree, recommends South Boston’s Pretty Reckless boutique for accessories, Goorin Bros. for men’s and women’s hats, and larger shops like Zara and Banana Republic for classic white attire.

And lest you think that dining al fresco in a fascinator might be a bit fussy, not so fast: White can be practical, too.

“There’s a level of classiness that comes with holding a glass of wine in your hand, and maybe you’re a little tipsy, but you won’t have a stain on your clothes at the end of the night,’’ says Meneide with a chuckle.

Kara Baskin can be reached at kcbaskin@gmail.com. Follow her on Twitter @kcbaskin.