On a Saturday last fall, a Mexican American teenager in Corpus Christi, Texas, had everything planned out for a coming-of-age party. It would have custom-made jewelry, a string quartet to play renditions of pop songs and a group of high school freshmen in black tailcoat tuxedos to perform a dance.

This may sound like a classic quinceañera for a 15-year-old girl marking her transition to womanhood. But on that day, the spotlight was on Javier Calderon, a 15-year-old boy celebrating becoming a man.

Mr. Calderon is part of a growing number of young Latin American boys embracing the centuries-old tradition that until recently has been reserved for girls — a trend that represents one way that Latinos are adapting the custom in the United States.

“I wanted to show everyone what I wanted to be,” Mr. Calderon said. “I’m turning into a teenager.”

Some boys are asking their parents for a party of their own. Mothers without daughters are begging their sons to have a quinceañero, the name of the celebration for boys. At times, the idea that a boy should have his own party has been contentious, especially for older Latinos who deeply value tradition.

Quinceañeras typically celebrate a girl’s entry into adulthood on her 15th birthday, with the term deriving from the Spanish word quince, which means 15. The parties tend to be elaborate and big, and can cost as much as a wedding.

Quinceañeros have been no exception — some parents are spending up to $70,000 to host them for their 15-year-old boys. And some see these parties as a way to push back against the socially conservative gender roles many Latinos grow up with.