Getting kids to rumba? You bet.

Filmmaker Marilyn Agrelo could never have predicted that she would make a movie about children, let alone ballroom dancing, until her filmmaking partner presented her with an irresistible subject.

Agrelo's acclaimed documentary "Mad Hot Ballroom" - based on a newspaper story written by coproducer Amy Sewell - follows three classes of New York City fifth graders from different economic and cultural backgrounds over 10 weeks as they learn to dance and vie for the 2004 title of citywide champions.

"Amy's enthusiasm was very persuasive," says the director. For Agrelo, who was born in Cuba and grew up in New York, the film was less about children learning the rumba and the fox trot and more about exploring the city's diversity. "I wanted to contrast their neighborhoods, their lifestyles, their attitudes, all these things."

After visiting 20 public schools, the two women narrowed their focus to classes from Tribeca (the trendy area that was the focus of Sewell's 2003 story in the Tribeca Trib), Brooklyn (where the working-class population has shifted from predominantly Italian to Asian-American), and Washington Heights (the impoverished neighborhood that had nearly snagged the winning trophy a year earlier). Agrelo was especially drawn to Washington Heights teacher Yomaira Reynoso and her students, recent arrivals from the Dominican Republic who spoke little or no English.

"The stakes are so much higher there," says the documentarian. Ninety-seven percent of the local school's families live at poverty level or below. "They have loving families, but they really have to fight to have an equal footing with many of the other kids."

What they do have is a strong cultural connection to many of the dances. Agrelo, too, had a personal connection to the musical tradition: Her aunts and uncles loved to dance the merengue at family gatherings during the filmmaker's childhood. "Dance is a part of life," she says.

She suspects that the movie resonates with audiences in part because it takes adults back "to that time in your life when you were first thinking about the opposite sex and how scary and weird all that was. It's a very magical little time."

Awkward, too. In Brooklyn, the Asian girls' hands often hovered three inches above their partners' shoulders for the first few lessons. At every school, the girls (often towering over their shorter partners) complained that the boys weren't up to the job of leading. "Girls at that age don't think the boys are very smart," says the director.

There are hints of the darker issues that lie just ahead in adolescence. A boy quits dancing for basketball and teases a male classmate by calling him gay. A girl ponders what a strange thing it is that women have to be pregnant. Girls from Washington Heights voice fears about walking past leering men on the street.

Agrelo didn't want to dwell on the dark things, feeling a certain protectiveness toward the young dancers, but alert viewers will notice the undercurrents.

"It's little things like when these girls in Washington Heights talk about boys and girls - it's not quite as whimsical as when the other kids talk about it," she says. "What they say is that they hope their boyfriends are not drug dealers."

Some believe the students are too young for the competitive pressure. One team - and their teacher - collapsed into a sobbing heap after they failed to advance. "It was very hard to shoot that, but we couldn't back off because it meant so much to them," she says. "It ended up being a moment people talk about and remember."

Overall, Agrelo feels the lure of citywide recognition helped the kids bond as a team. She says: "Competition is something that is going to be in your life forever in one form or another."

While school arts programs across the country are being cut, the ballroom dance program, now 10 years old, is flourishing in New York. Agrelo believes it's not because of the dancing itself, but because of the ballroom-dance rituals, the behavior it models, and the politeness between the sexes that they might not see and learn at home.

"There's something about the 'ladies and gentlemen' aspect of it," she says. "Telling a boy he has to escort his partner to the other side of the room, that he needs to take care of the lady, that he needs to look in her eyes, bow to her, and give her his arm, it's almost revolutionary."