Powered by granola bars and bottled water and doted on by car-pooling mothers, these young singers are ambassadors for the city, working to promote change.
In 2004, they preceded a speech by Barack Obama at the Democratic National Convention in Boston. When the city's new superintendent of schools arrived from Memphis, they greeted her. They have toured Mexico and Japan.
Recently, they hosted Czech choristers and welcomed King Abdullah of Jordan.
Tomorrow they will take center stage at the New England Conservatory's Jordan Hall to sing in the fifth annual Martin Luther King Jr. Concert. With the theme "Remember Yesterday, Inspiring Tomorrow," it is billed as the climax of the chorus's season and will be broadcast on WCVB-TV (Channel 5).
And just who are they? They call themselves BCC, short for the Boston Children's Chorus.
Their history began with one man, Hubie Jones, who came here to study social work at Boston University in 1955. The next year, he visited Jordan Hall, where he first heard Martin Luther King Jr. speak.
"I'll never forget that day," Jones said. "I was sitting right in the middle of the orchestra section. [King] just set me on fire. It was one of the most unbelievable speeches I've ever heard. It filled me with hope and pride, and I made a commitment to social change in this country."
Inspired by King, Jones went on to work for racial justice and the quality of life in the city.
It was 10 years ago that Jones first listened to the Chicago Children's Choir and was "blown away by a very diverse group of young people, high school kids singing at a level of artistic excellence."
"I felt like Boston needed a diverse chorus group to lead them to excellence as the result of good instruction," Jones said.
So he founded the Boston Children's Chorus. He recruited about 100 children, found an artistic director and other staffers, and rehearsals started in 2003.
"They would serve as ambassadors for the city, playing at public as well as private events," he said.
Then he decided to invite the Chicago Children's Choir to join forces in Boston for the King holiday in 2004 - and they have returned every year since.
"We want people to know that we have to do things on MLK Day that are reflective and powerful," he said.
The Boston chorus now has several choirs, with about 300 members from more than 60 neighborhoods in the city and suburbs, representing a range of incomes, religions, and cultures. The children, ages 12 to 18, perform 40 to 50 programs a year.
"We never turn anyone away who can't pay," said Mary Ann Brennan, director of development and marketing for the nonprofit group. "Some people only pay $3 a month. Some people don't pay at all. Money never stops someone from being in the chorus."
Today, many families involved believe that the Boston chorus embodies the ideals of King.
Near the end of a recent weeknight rehearsal, mothers of chorus members waited in the foyer of the Shawmut Avenue headquarters, where the chorus moved last July from its previous home on Chauncey Street. One mother brought a cheese pizza for her hungry children, and shared it with others.
"Some of us have developed really good friendships through this," said Kerry Thompson of Melrose, whose 14-year-old daughter, Grace, is in the premier choir. "A lot of these kids now go to each other's plays and sleep over at each other's houses. This concert [tomorrow] captures that spirit of love in a way that's hard to describe."
For the concert, Grace will sing "Dravidian Dithyramb," a composition that proclaims unity and combines a drum beat from northern India with a melody from southern India.
Recalling previous Martin Luther King Day concerts, her mother said, "people are getting on their feet and clapping. . . . It reminds me of the 'We Shall Overcome' days."