From the outside, Lockerman-Bundy Elementary School looks forbidding, a tan monolith built in the 1970s. Some of the rowhouses across the street are boarded up — reminders of the cycles of poverty and abandonment this city has struggled with for years.

Inside on an afternoon last month, though, it was a different story. Music echoed through brightly colored halls lined with murals. Classes were over, but school was not out: Young string players rehearsed Beethoven in one classroom, while flutists practiced in another and brass players worked on fanfares in a third. Also on offer were homework tutors, an after-school snack and dinner.

“Four measures for nothing,” Wade Davis, a cello teacher, called out to his young string section, launching them into Beethoven’s “Ode to Joy.” Standing outside the classroom, Carol Moore wiped away tears as she peered through the doorway at her son, Jayden, 11, who was playing viola.

“I’m so proud of all of them,” she said.

It was just another afternoon at OrchKids, the free after-school program that the Baltimore Symphony Orchestra and its music director, Marin Alsop, started a decade ago with just 30 children in a single school. The program now reaches 1,300 students in six schools; its participants have gone on to win scholarships to prestigious summer music programs; play with famous musicians, including the cellist Yo-Yo Ma and the trumpeter Wynton Marsalis; perform at halftime at a Baltimore Ravens game; and win accolades at the White House.

The program was the idea of Ms. Alsop, who began thinking about how to forge closer ties to the city soon after she became Baltimore’s music director — and the first woman to lead a major American symphony orchestra — in 2007.

“I’m deeply distressed that our concert halls, our stages, don’t reflect the diversity of our communities,” she said in an interview. “How are we going to change that landscape?”

She got the program off the ground by pledging $100,000 of her own money — part of a MacArthur “genius” grant she won in 2005 — as a match to encourage other donors. There were bumps along the way. The first school to house OrchKids was shut down after a year, forcing the program to replant itself at Lockerman-Bundy.

The first student to enroll in the program was Keith Fleming, then a first grader. “At first I didn’t really like music,” he recalled recently. “I just thought, I’m going to do this because I didn’t really have something else to do. The first day came, and I started to learn music — and I started to like it.”

He is 15 now, and his tuba skills have taken him to Austria and London and helped him win an audition to the Baltimore School of the Arts, where he is a sophomore.

Asia Palmer, a flute player in her 10th year with the program, said that for her the highlight had been meeting Michelle Obama at the White House in 2013, when Ms. Palmer accepted an award on behalf of the program.

“The program has given me a voice,” she said. “I feel like I can be whatever, do whatever — strive.”

OrchKids offers a respite from troubles that often come disturbingly close to home; in 2015, five people were shot just a block from the school, close to dismissal time. It is also a bright spot in a city that has seen more than its share of troubles — including the 2015 death of Freddie Gray, a black man who died of a severe spinal cord injury while in police custody; the riots that followed; and being named the city with the highest per capita murder rate in 2017 by USA Today.

The program was partly inspired by El Sistema, Venezuela’s free music education program, which Nick Skinner, the OrchKids director of operations, visited to get ideas for the program. These days El Sistema’s future in Venezuela, which is facing a grave economic crisis, is in some doubt. But its ideals have taken root elsewhere.

“From the very beginning,” Mr. Skinner said, “it was very important that we were immersed in the school, and in the community.”

In 2005, the Baltimore Symphony began playing some of its concerts at Strathmore, in North Bethesda, Md., a suburb of Washington, making it the rare orchestra with two homes. OrchKids showed that its commitment to its hometown remained strong.

The orchestra has enjoyed recent artistic successes — it will tour Europe this summer for the first time in 13 years — but, like many ensembles, it has struggled financially. Its annual budget of just over $28 million is less than half of the New York Philharmonic’s.

But it spends more than $1 million a year on OrchKids, said Peter Kjome, its president and chief executive officer. The program, he said, appeals to some philanthropists who don’t give to traditional performing arts organizations but do support educational and social justice initiatives.

This year the orchestra announced a $65 million fund-raising drive — $10 million of which will be devoted to OrchKids and its youth orchestra program. Ms. Alsop wants OrchKids to grow to 5,000 students in the next five years, and 10,000 in the next 10. (“They don’t like it when I say these things,” she said wryly.)

The program celebrated its 10th anniversary earlier this month with a concert at the neo-Classical War Memorial, across from City Hall. In the audience was Kimberly Hill-Miller, the principal at Lockerman-Bundy. She said the program had benefited the school in ways that went beyond music, noting that students who joined OrchKids generally had better attendance and academic performance than their peers.

“Kids need some kind of outlet,” she said. “It’s definitely needed.”

Baltimore’s mayor, Catherine Pugh, not only attended the concert but also picked up a pair of drumsticks to jam on the steps of the War Memorial with the OrchKids bucket band, led by Brian Prechtl, a Baltimore Symphony percussionist.

“Every time they step out, they’re a positive image of our city,” said Ms. Pugh, who added that she would like to see OrchKids expand.

Then it was time for the concert in the grand marble hall. Shortly before taking the podium to conduct an orchestra of nearly 250 students — some seated at a row of short, child-friendly harps — Ms. Alsop thanked the parents, teachers, school staff, donors, politicians and volunteers present.

“When people say, ‘Oh, you’re from Baltimore,’ they have that look,” Ms. Alsop told the audience. (Some nodded knowingly.)

“I tell them that Baltimore is about community,” she went on. “Baltimore is about possibility. Baltimore is about future.”

Then she led the young orchestra in a mash-up of the “Ode to Joy” and “Conqueror,” by Estelle. The practice at Lockerman-Bundy had paid off. The kids brought the house down.