The 2006 film about a gay teenager at a quinceañera is Quinceañera.
Written and directed by Richard Glatzer and Wash Westmoreland, the film follows Magdalena, a teenager in Los Angeles whose family becomes more complicated as her fifteenth birthday approaches. The story also centers on her cousin Carlos, who is gay, and their older cousin Auntie Tomás.
Quinceañera premiered at the 2006 Sundance Film Festival, where it won both the Grand Jury Prize and the Audience Award in the dramatic competition. Those awards helped draw attention to the film before its wider release.
The movie uses the birthday tradition as a setting for questions about family, sexuality, religion, class, and belonging. It is sometimes confused with similarly titled Spanish-language television productions, but this independent American drama is specifically the 2006 Sundance-recognized film.