The sound of rustling and muted conversation can be heard coming from the dressing room at Fashion Corner in Sunnyside. In the nearby waiting area, Roque Arriaga sits patiently as 2-year-old Evelyn races around, looking at the rainbow of dresses packed onto racks that seem to extend forever.

Finally, the door opens and Roque's daughter Nancy walks out, a girl transformed into a princess, complete with a crown. Her dress is robin's egg blue and flares out like a bell from the waist to the floor, in a cascade of ruffled chiffon. The bodice is covered with sparkling gems and fits her trim waist like it was made for her. She can't stop smiling and her mother Griselda beams proudly as she follows her out.

This is a moment that Nancy and Gris will never forget. As Nancy twirls and gazes at her reflection in the mirror, the reality begins to sink in. Nancy is no longer a girl. She is becoming a woman, and will soon take part in the ceremony that marks a bright line between the two: The quinceañera.

Quinces combine a church ceremony with a huge party afterwards, to celebrate a girl's 15th birthday and her transition into adulthood. This passage is marked by many traditions, including a gift of the last toy of childhood, and changing from the flat shoes she wears to church into adult high heels for the "first dance" with her father. She has a court of honor, composed of girls called Damas, and boys called Chambelanes, who dress in formal clothes coordinating with her dress.

"I'm happy, excited, words can't explain how happy I am," Nancy says. "It's my dream dress." The saleswoman ushers the family towards the fitting area, where a wall of mirrors reflects them. Gris flits around Nancy, adjusting the dress and fluffing out the skirt. She says she's excited and sad at the same time. "Oh my gosh my baby is growing up already." She tears up. "She's talked about this since she was a little girl."

The dress is kept a secret. Girls are not allowed to show them to anyone or share pictures of them on Facebook until the big day. The saleswoman and seamstress have Nancy walk up and down the aisles, kicking it out at the hem as she practices walking in it.

Nancy says "You only turn 15 once and it's a tradition." The family started picking the venue, the photographer, the DJ, and the food around her 14th birthday. "I think we have everything ready," says Gris. "That's how we do it," she adds, "we just make payments here and there and we pretty much have it paid for."

As many as 400 people are coming to the party at the Satus Events Center in Toppenish. But a quince is far more than just a party. The girls have to be baptized, have their first communion and take a series of classes on the meaning of the quince and the church ceremony. They also have to do 20 hours of community service for church. Nancy didn't want to go to classes at first, but says "I'm starting to like them now. You learn how to be an adult."