BESS KARGMAN wasn’t expecting anything life changing when she walked into the Skirball Center for the Performing Arts on her lunch break from an unpaid internship one April day three years ago. When banners advertising the New York City finals of the international ballet competition Youth America Grand Prix caught her eye, this aspiring documentary filmmaker in search of a subject popped into the theater and grabbed one of the last available seats.


“Out onstage walks this itty-bitty, baby ballerina,” Ms. Kargman, 29, recalled in a telephone interview. “She was probably 4 feet 2. I’d never seen dancing like that at such a young age: such maturity, grace, composure, technique and artistry. Watching that little dancer gave me goose bumps.” Other viewers, Ms. Kargman thought, might have the same reaction. She walked out of the theater and decided on the spot: “This is my film. This is mine.”


That “baby ballerina,” Miko Fogarty, 11 at the time, became one of seven young competitors Ms. Kargman followed over the course of a year, as they prepared for the regional and final rounds of the Youth America Grand Prix, the world’s largest student ballet competition, which awards scholarships and, for a select few older students, company job offers.


The result is “First Position,” Ms. Kargman’s debut documentary. After receiving acclaim on the festival circuit this past year, “First Position” will be released by Sundance Selects in over 40 theaters across the country starting Friday.


“Growing up, this was always a film I wished existed,” Ms. Kargman said from Los Angeles, one of many stops where she is promoting the movie. A native of Brookline, Mass., she studied ballet intensively at Boston Ballet as a child — in high school and college she switched to competitive ice hockey — and loved both fictional and documentary ballet films.


While ballet has proved a fertile film subject over the years — from heavily dramatized films like “Center Stage” and “Black Swan” to acclaimed documentaries like “La Danse” and “Ballet Russes” — Ms. Kargman said none of them had shown what she really wanted to see: both the onstage and offstage lives of dancers, including their more mundane habits.


“To see what they eat, how may hours of sleep they get,” Ms. Kargman explained. “I was waiting for someone to create a film like this, and I guess I got tired of waiting.”


It would take some time for Ms. Kargman’s project to get off the ground. Convincing the Youth America Grand Prix to allow a film crew (it never had before) was a difficult task for a first-time filmmaker.


“We’re approached all the time by producers who want to make documentary or reality, and we always ask what they want to portray,” Larissa Saveliev, the organization’s founder and artistic director said, noting that the competition recently rejected a request from Lifetime’s popular “Dance Moms.” “Usually they want to see the fights, the teachers, anorexia. And we’re just not interested to have a film about this.”


Ms. Kargman, on the other hand, emphasized her ballet background, explaining, for instance, that she knew to film the entire body. “No. 1, she was a former dancer,” Ms. Saveliev said. “She won my heart with that. We spoke the same language.” Her dance expertise also somewhat compensated for her nearly nonexistent film résumé: a recent graduate of the journalism school at Columbia University, she had made one short film for class, about a child caught in the juvenile justice system.


“The majority of my friends were not keen for me to do this,” said Satoko Fogarty, Miko’s mother. “But I was really touched by what Bess wanted to do.”