NEW YORK, NY.- During rehearsals for New York City Ballet’s winter season, there was something very unusual about one of the choreographers creating a new dance. It wasn’t just that the person in charge was a woman, though that would have been uncommon until a few years ago. Nor was it that the choreographer, Tiler Peck, was one of the company’s star ballerinas, though that is still quite rare. The difference was what Peck wore on her feet as she made and rehearsed the work: pointe shoes.

Wendy Whelan, City Ballet’s associate artistic director, said that in her nearly 40 years with the company she had never seen anyone choreograph in pointe shoes before. Peck, who has been with the company 19 years, said that she had never seen anyone else do it, either. But that didn’t stop her.

“I don’t think that’s something that every choreographer has to do,” Peck said. But because she is wearing pointe shoes, “I can step in and show them. And if they tell me that something I want them to do can’t happen, I can be like, Actually, it can!”

Stepping in and showing were among Peck’s goals in creating her new ballet, “Concerto for Two Pianos,” which has its debut on Feb. 1. While she has made work elsewhere, this is her first piece for her home company. “It’s my opportunity to pass on to the next generation anything that’s been given to me,” she said.

“I know as a dancer all I want is to be challenged and continue getting better,” she added. “So I wanted to use the technique of these dancers and push them. I wanted to make something that they will want to dance every night.”

She started with the music: Francis Poulenc’s “Concerto for Two Pianos and Orchestra.” It’s a bright, exuberant score of racing virtuosity, Mozartean melodies and patches of mystery. It sounds like music that Peck, an omnicompetent technician known for her time-bending mastery of musical phrasing, would enjoy dancing to herself, and her choreography attends to it actively.

To cast the work, she said, all she had to do was listen. In the concerto’s full-throttle piano runs, she saw the whirlwind bravura of Roman Mejia. In its dramatic sections, she envisioned a pairing of Mira Nadon and Chun Wai Chan. In the more flippant parts, she imagined India Bradley and Emma Von Enck.

Such imagining was possible because Peck, 35, knows these dancers, all younger colleagues, so well — their strengths and weaknesses, their untapped potential. About Bradley, for example, she said: “People don’t think that she can do the hard technical things. She can, and I want to show that. Having her next to Emma is good for both of them, because Emma is so technically gifted but needs more fullness.” With Nadon, Peck has been working on finesse: in-between steps, rolling through the foot, the details that can turn a gifted ballerina into a great one.

In Peck’s role as choreographer, she also plays coach. “I get to say all the things I’ve wanted to say when I watch them dance,” Peck said. “Normally, that’s not my job, and I would never want to overstep, but in this space I’m able to, and I get so much satisfaction out of seeing somebody improve.”

Whelan has noticed the effect. “Tiler is really digging into these details that I’ve watched her work on in her own dancing over the years,” she said. “She’s building these little birds on the dancers’ shoulders that they will have for the rest of their careers. They’ll have Tiler’s voice.”

And it isn’t just words. In recent rehearsals, when something wasn’t to Peck’s liking, she often joined the dance herself — in those pointe shoes — to solve the problem physically and then teach the solution to the dancers.

“Tiler has such amazing coordination and can kind of make anything happen in her body,” Nadon said. “But then she can communicate how to do it, and since she’s in tune with the way we dance here and we all speak the same vocabulary, we understand immediately.”

In rehearsals, Peck was friendly but firmly in charge, prepared and efficient. Many of her corrections came with laughter and maybe an eye roll. “She knows when we’re faking something,” Nadon said.

“She makes the space feel very comfortable,” Mejia said, “but she will push you to your limit as well — faster, higher. Anything she says will make you a better dancer.”

As confident as Peck was at the front of the room, she did not always think of herself as a choreographer. As a child at her mother’s dance studio in Bakersfield, California, she made dances in many styles, especially jazz. Whelan remembered about 15 years ago when she met Peck’s mother and was praising her daughter’s talent — “her mom said, ‘She also choreographs.’”

But, Peck said, “I didn’t think that meant that I would be able to choreograph something on a classical company.” It wasn’t until 2018 that Damian Woetzel, a former City Ballet star and a mentor to Peck, invited her to make a piece for the Vail Dance Festival, which he directs. (He is also president of the Juilliard School.) “If he had not given me that push, I don’t know if it ever would have happened,” she said.

Since then, Peck has made more works for the Vail festival, as well as for Boston Ballet and Northern Ballet in England. She conceived and directed a dance program at the Music Center in Los Angeles, an experience captured in the documentary “Ballet Now.” Last year, she presented some of her choreography as part of a program she directed and curated at New York City Center.

When the invitation from City Ballet came, Peck felt ready, she said. While the Music Center and City Center programs mixed ballet with tap and hip-hop, and her resume includes appearances on Broadway, she was sure that she wanted her City Ballet debut to be a classical work. The only part of the process that made her nervous was using a large ensemble, or corps, for the first time. (This one has seven couples.) “When you add in the second cast, that’s a lot of people in the room,” she said. “But after 10 minutes I could see that they were enjoying themselves and I calmed down.”

“I feel like the steps I’m giving them are the steps I would give the principal dancers,” she continued. “I think they feel pushed.” She has been following a directive from another mentor, choreographer William Forsythe, who told her: “Don’t let them just run to their places. Make them dance.”

In an email, Forsythe explained that it was important “to fully choreograph all transitions.” He also offered a vote of confidence, writing that Peck’s extensive exposure to the George Balanchine repertoire was “one of the best schools imaginable for a ballet choreographer.”

The choreographic process was difficult for Peck for another reason, though. Two days before her first scheduled rehearsal, her father died. She postponed the start by a day, which she spent listening to the music. Then she got to work with the dancers.

“I made the steps that I heard in the music, and it was pouring out of me,” she said. “It was cathartic — to be able to do the thing I love, surrounded by people I love and respect. It was a hard time, but I looked forward to being in the room every single day.”

That rehearsing had to be squeezed in among Peck’s many other rehearsals. This is another way to understand Peck the choreographer wearing pointe shoes. She is in no way done as a dancer. This City Ballet season she is performing in nine works. She pulled herself out of a 10th — saying no was hard, she said — because it was on the same program as her premiere.

“I wanted to be able to sit in the front and enjoy watching the piece and take a bow not in warmup clothes,” she said.

Peck is often asked why there aren’t more active ballerinas who choreograph. “And I’m like, ‘I’m supposed to be in front of the room for an hour and a half and then go rehearse ‘Swan Lake’?” she said. “It’s not physically possible. It’s easier for men. The pointe shoe adds so much more difficulty.”

And then, having rehearsed her “Concerto” and given an interview, she went off to rehearse her dancing in Balanchine’s “Ballo della Regina,” one of the most technically demanding ballerina roles in City Ballet’s repertoire. The pointe shoe may add more difficulty, but that, it seems, is nothing Peck can’t handle.

This article originally appeared in The New York Times.