'I'm such a nerd," said Julie Diana, a principal dancer with Pennsylvania Ballet, who recently saddened fans by announcing that she would retire after Sunday's performance of the ballet's "Director's Choice" program at the Academy of Music.

Nerd is hardly the term that comes to mind. Diana is well known for her portrayals of the quintessentially romantic heroines in Romeo and Juliet and La Sylphide. She is also a versatile and exceptionally intelligent dancer who excels in sizzling, Broadway-style roles (as in Slaughter on Tenth Avenue) and can bring an audience to tears in abstract works like Christopher Wheeldon's After the Rain. Offstage, the 2008 graduate of the University of Pennsylvania (summa cum laude in English) maintains the rigorous schedule of a professional ballerina, is establishing a career as a freelance writer, and is raising two young children. Nerd?

Diana discussed her life and career last week in a public Q&A at the Philadelphia City Institute branch of the Free Library, then in an interview at the ballet's spacious new school on North Broad Street.

On both occasions - whether poised and elegant in killer pumps and a chic navy blue frock, or slightly frazzled in jeans, sneakers, and no makeup before an early-morning class - Diana looked much younger than her 37 years. And in both venues, she readily dissolved into girlish giggles, told funny stories, and turned radiant when talking about her husband, fellow ballet principal Zachary Hench, or their children.

Spending more time with her family is one reason Diana is retiring. Another is the toll ballet takes on the human body (her chronic hip injury will soon require joint replacement).

And it may not be coincidental that Roy Kaiser, the ballet's longtime artistic director, is also stepping down. While she credits her husband with making it possible to manage both family and career, Diana also acknowledges her boss: "Roy has been incredibly supportive," she said, giving her the time off that she needed during both pregnancies and after two C-sections.

Diana, a native of Verona, N.J., was a ham by age 3 ("I remember pink sequins and bunny ears," she reminisced, "and shaking my tushy"). She started ballet at 7, after rejecting gymnastics ("I was terrible," she maintains; more important, she was afraid of heights). Since then, her life has been focused on the studio - first at New Jersey Ballet, then at the School of American Ballet in New York City. At 16, she was invited to join the San Francisco Ballet, where she stayed until coming to Philadelphia in 2004.

A similar trajectory could be found in the resumés of many other ballet stars. What sets Diana apart is her absolute commitment to the emotional core of every part she dances. As she says, "I love to tell a story onstage and lose myself in the role."

She honed this skill in San Francisco, where she worked with the great British ballerina Lynn Seymour. This "gifted actress," she recalls, "taught me how to communicate with my hands, first."

"Talk with your fingertips," Seymour would say, and to this day, Diana's hands are particularly expressive.

Another of Seymour's invaluable exercises involved talking, even screaming, in rehearsal. "Of course, I didn't scream onstage," Diana notes, "but I remembered how it felt when I screamed." Seymour also encouraged Diana to "always have a monologue running in my head while I'm dancing. I actually think, 'Do you love me?' as a way to stay in the moment."

Diana has a positive attitude toward leaving the ballet stage. "A dancer's life is short," she says matter-of-factly, "but I think this is good. After retirement, we still have lots of time and energy to do other things."

Physical movement will remain an important part of her life. She expects to continue teaching ballet and practicing Hatha yoga. She thinks about dancing on Broadway and joked that she and Hench might take up ice dancing ("even though I've never put on a pair of skates").

Diana's ambitions extend beyond dance. "I'm not limiting myself in any way," she says of her future. She has written extensively about dance and is contemplating a novel, a memoir, or a combination of both. She also is interested in honing her leadership skills; since 2012, she has served as president of the University of Pennsylvania's Alumnae Association - significant for someone who used to be "petrified" of speaking in public. "It has taught me a great deal," she says, "how to lead a board meeting [and be] the face of an organization at public events."

Finally, she becomes a bit tearful discussing her final Pennsylvania Ballet performance, when she dances Wheeldon's After the Rain with her favorite partner, her husband, as their children watch in the audience. It will be Mother's Day.


Director's Choice

7:30 p.m. Thursday and Friday, 2 and 8 p.m. Saturday, and 2 p.m. Sunday, at the Academy of Music, 240 S. Broad St.

Tickets: $30-$135. Information: 215-893-1999 or www.paballet.org.EndText