Amid wailing bagpipes and roaring applause, the newest batch of New York City firefighters graduated from the fire academy on Thursday, joining a 148-year-old institution that is steeped in tradition, but also on the cusp of significant change.

The graduation was the latest stage in a court-ordered experiment to alter the face of the predominantly white Fire Department. Minorities make up more than 60 percent of the class, making it the most diverse in department history.

The new class is “furthering the department’s longstanding goal of better representing the city we serve,” Salvatore J. Cassano, the fire commissioner, said at the ceremony, which was held in the packed hall of the Christian Cultural Center in Canarsie, Brooklyn.

“I believe in diversity,” he said. “I believe it will make our work force stronger.”

The effort to diversify has met with skepticism and some hostility in some of the city’s 200 or so firehouses. Some firefighters have accused the department of creating a quota system that has promoted diversity over competence.