Tenor Jeffrey Thompson, right, with members of the New York Baroque Dance Company in rehearsal for Opera Lafayette’s production of Rameau’s “Les Fêtes de l’Hymen et de l’Amour.” (Louis Forget)

The baroque dancers wore 18th-century costumes and carried garlands of flowers, looking as if they had stepped out of a painting by Watteau. The Indian dancers were wrapped in gauzy muslin, picked out with gilt and brilliant blue, and the bells on their ankles emitted clusters of sound each time they stepped. The contemporary dancers, in blue bodysuits swirled with silver, were the irreverent sprites of the group: They played, among other things, the role of floodwaters, and undulated even when they stood still, like fronds of seaweed in a current.

The event that brought these three disparate ensembles together was a French baroque opera.

This year is the 250th anniversary of the death of Jean-Philippe Rameau and the 20th anniversary of Opera Lafayette. It makes perfect sense that the one should celebrate the other. Opera Lafayette, which started in the Capitol Hill basement of its conductor, Ryan Brown, has turned into an internationally recognized company precisely because it performs work that hardly anyone else is doing. Rameau is one of the most important French composers, but you’re unlikely to see his work at the Washington National Opera or the Metropolitan Opera, compelling as much of his music may be.

You have to turn to specialty groups such as William Christie’s or Opera Lafayette, whose period orchestra, sometimes a little lurchingly but with overall elegance and flair, offered “Les Fêtes de l’Hymen et de l’Amour, ou Les Dieux d’Égypte” at the Kennedy Center Concert Hall on Monday night.

The name doesn’t exactly trip off the tongue, and the opera doesn’t exactly fly by, either. First presented as part of the celebration of the marriage of the Dauphin of France in 1747, it suffers from the longueurs and occasional stasis of occasional music written for occasions long forgotten. Rather than a single dramatic story, it’s a sequence of vignettes with singing and plenty of dancing, all showing conflicts resolved by love between gods and men: Amazons vs. Egyptians; a river god vs. the mortals who want to sacrifice his beloved; and finally the arts vs. each other, more or less.

Bass François Lis and soprano Ingrid Perruche in rehearsal of Opera Lafayette’s production of Rameau’s “Les Fêtes de l'Hymen et de l’Amour.” (Louis Forget)

So the dancers — or rather, the contrasts between them — ended up carrying the evening. The main group, the New York Baroque Dance Company, led by Catherine Turocy, is a longtime Opera Lafayette collaborator, but the company was challenged in new ways by the contrast with Kalanidhi Dance, led by Anuradha Nehru, who entered as the Amazons, and by the Seán Curran Company, the sinuous floodwaters unleashed by the river god.

A Kalanidhi company member would enter into a duet with a Baroque dancer and execute the same moves with her own distinct physical accent. The Curran Company members picked up a little bit of everyone’s physical idiom. The final scene, of the artistic contest, evolved into a genuinely captivating dance-off that was interrupted by the soprano Claire Debono, who burst into the proceedings with an aria that (in the story, at least) stopped the action and won the contest.

Debono, with a lyrical round crystalline sound that had patches of tautness, was one of the evening’s notable singers; another was the resonant bass-baritone François Lis, clad in the river god’s scanty toga. Jeffrey Thompson, as the god Osiris in the Amazon scene and Aruéris, god of the arts, in the final scene, was a distinctive presence; he embodied the effort it took to get the vocal line out of his body, contorting his head and shoulders and pulling out the line, both in its dynamics and intonation, like taffy.

Ingrid Perruche had a nice warm voice as Memphis. If the evening wasn’t quite as exciting as some of the company’s other offerings, it’s partly because the company has been rising to ever greater dramatic ambitions, offering fully staged productions of neglected 19th-century works, such as Grétry’s “L’Épreuve Villageoise,” which will close the company’s season in the spring with an evocation of period New Orleans. Stay tuned for the 25th anniversary.