Isabella Boylston and James Whiteside star in a revival of the rarely-performed ballet, 'Harlequinade.' (Rosalie O'Connor/Rosalie O’Connor)

Classical ballet is not big on happy endings. As you may recall seeing through mascara-stained tears, “Swan Lake,” “La Sylphide” and, of course, “Romeo and Juliet” all typically end with the leads dying in the arms of their respective lovers.

With “Harlequinade,” opening at the Kennedy Center on Tuesday, American Ballet Theatre is lightening things up with a funny ballet full of physical comedy. There’s even a happy ending: The hero gets the girl — and, judging by the dozens of children who twirl across the stage after the wedding, you can assume they go on to have a huge family.

Originally staged in 1900 as a private entertainment for the Russian tsar and his court, Marius Petipa’s “Harlequinade” went on to be a huge hit. A series of pantomime sketches and dance set pieces pinned to a barely-there plot (Harlequin wants to marry Columbine; Columbine’s father wants her to marry some rich old dude instead), “Harlequinade” played to enthusiastic audiences for nearly two decades. Then, it was largely forgotten.

That is, it was until American Ballet Theatre choreographer Alexei Ratmansky dug up and deciphered the original steps of the ballet — movements that had been written down by Petipa using an obscure notation system. Ratmansky also enlisted designer Robert Perdziola to create costumes in keeping with the originals.

“I really went down the research rabbit hole, looking at all the sketches and photos I could find,” Perdziola says.

The costume designer immediately saw that this was going to be a big job. Unlike most ballets, “Harlequinade” calls for a lot of accessories, including wigs, masks, hats and gloves. Additionally, the costumes are more cumbersome than what dancers are used to today — men in “Harlequinade” wear collars and ruffs; women wear mostly knee-length dresses and lots of layers. In the second act, there are even a few dancers in floor-length gowns with trains.

“I was so worried about those trains,” Perdziola says, “But the ABT dancers are so good, no one tripped, at least not that I saw.”

Hats have gone flying on occasion, but “Harlequinade” theatrical costumes are worth the technical challenges they present, Perdziola says, because they help emphasize the ballet’s roots in commedia dell’arte, a popular form of Italian theater at the time.

“All the characters in ‘Harlequinade’ are commedia dell’arte stock characters,” he says. “The original audience would have recognized them instantly.”

Today’s audiences might not be quite so familiar with the types, so we asked Perdziola to break them down for us.

Harlequin (Robert Perdziola/Robert Perdziola)

Harlequin: The main character of “Harlequinade” is a trickster, and his energetic and vibrant costume reflects his personality. “We had it all digitally printed. But then I also got bits of actual fabric — like stretch velvet and stretch corduroy — to apply on top,” Perdziola says. “So as the figure turns, it’s like a faceted surface that catches the light.” In the design sketches for the original “Harlequinade,” rabbit feet hang from Harlequin’s hat, but photos from the production show tassels instead. Perdziola followed the same path, originally trying for rabbit feet but then switching to tassels. “The feet were too cumbersome,” he says. A traditional part of Harlequin’s costume in other commedia dell’arte productions, the rabbit feet may emphasize the character’s quick wit. Also, notice the character’s stick, which he occasionally slaps on the ground — the origin of the word slapstick.

Pierrette (Robert Perdziola/Robert Perdziola)

Pierrette: One of the smartest characters of the bunch, Pierrette is always sharply dressed. She’s also the unlikely consort of sleepy Pierrot, whom she constantly harangues and hits with her fan. “She’s just got a lot of style. She comes out and you think, ‘OK, I see who is driving this relationship,’ ” Perdziola says. Pierrette’s outfit for this moment in the original productions of “Harlequinade” was a dress and a jacket, but Perdziola streamlined it all into one garment for the ballet’s revival. “The original seemed kind of clunky to me,” he says.

Columbine (Robert Perdziola/Robert Perdziola)

Columbine: Another smart and smartly dressed woman, Columbine uses her wits to avoid the amorous overtures of other characters. The hat in her Act I costume was a particular challenge, Perdziola says, as it threatened to fall off the dancer’s head. So he eventually created a version that gets pinned to the dancer’s wig from the inside, and then flips closed like a lid. “It really needed to stay at that jaunty angle, which is hard to do,” Perdziola says.

Pierrot (Robert Perdziola/Robert Perdziola)

Pierrot: Sad clown Pierrot’s droopy sleeves telegraph his sleepy character. “He’s kind of the fool of the neighborhood. He’s not the brightest wit,” Perdziola says. Pierrot’s huge, ridiculous hat helps the dancer get into a clownish mindset. “You put that on and it frames the head. Instead of a nuisance, it becomes part of the character.”