Jerome Robbins in 124 Costumes and 30 Minutes

NEW YORK — Have you seen the guest list for Jerome Robbins’ 100th-birthday bash at New York City Ballet? It’s a who’s who of Broadway’s golden age: Tony and Maria, Anna and the king of Siam, the bottle-dancing men of Anatevka.

They are among the cast of characters represented in “Something to Dance About,” a tribute put together by Warren Carlyle that nods to nine of Robbins’ Broadway shows. The half-hour piece, which has its premiere Thursday at City Ballet’s spring gala, features 30 dancers in 124 costumes.

It’s the kind of lavish production value typically reserved for story ballets like “The Sleeping Beauty” and “Swan Lake.”

Marc Happel, the director of City Ballet’s costume department, said this was the biggest workload he’s had for a one-act ballet since he joined the company 12 years ago. “It’s an evening-length ballet done in 30 minutes — with the same number of changes,” he said during a recent visit to his workshop at Lincoln Center.

With a little more than a week to go before opening night, Happel’s department opened its doors to us for a glimpse at fittings and last-minute touches on the costumes from beloved musicals like “The King and I,” which in Carlyle’s piece includes principal dancer Tiler Peck wearing a dress roughly 5 feet in diameter for the number “Shall We Dance?”

As she twirled in her golden Anna dress, Peck said she wasn’t sure about the puffy sleeves. But then again, she never is.

“We have a joke here,” she said: Whenever she is in a new ballet and her costume includes sleeves, she pushes to have them taken off. “We like to say that when I retire, they’re going to give me all the sleeves they had removed.”

But Anna’s sleeves have been a part of the dress for months. Typically, the costume department begins work on a new ballet about six weeks before the premiere. Planning for “Something to Dance About” began late last year when Toni-Leslie James, a Tony Award nominee who is also at work on the costumes for “Othello” at the Public Theater’s Shakespeare in the Park, was brought on as the designer.

Her process begins with sketches, which she said were inspired by the original Broadway productions while not adhering to them too strictly. (The men of “Fiddler on the Roof,” wearing all black and no hats, are more abstract than in a typical revival.) Then James sources materials and commercial clothing from around the internet.

“Ten or 20 years ago, sourcing all these different types of costumes would be very difficult,” she said, adding with a laugh: “Now I can find most of this on Etsy.”

James’ ideas were brought to life by City Ballet’s costume shop, a department of 18 people: Happel, a shop manager, 11 stitchers, three drapers, a dyer and a shopper. They have been working on the 124 costumes since early this year (with a break during March) while also juggling designs for other ballets, including a new work by Justin Peck that will also have its premiere at the gala.

Their work spaces were filled with identifiable bits of Broadway, like Maria’s white dress from “West Side Story” hanging from the ceiling, or Tony’s mustard-colored jacket from the musical’s “Dance at the Gym” scene resting on a mannequin.

Emilie Gerrity, a soloist, visited the costume shop to try on her “West Side Story” costume, a dress designed for “Dance at the Gym” that with rapid modifications can be transformed for the skirt-swishing “America.”

She needed a moment of privacy to change into her Charleston-friendly costume for “Billion Dollar Baby.” It was only about 40 seconds before the fitting-room door was open again. (She repeated the trick later with a dress from “On the Town.”) Her dog, Freddy, looked unimpressed from his perch on a couch. But the humans in the room were awed by how quickly she was able to get from one dress to the next.

Still, the change will need to be even faster on opening night, Happel said: “It actually has to be about half that time during the show.”