When the Manassas Chorale ended its concert last weekend with the song “Why We Sing,” its members could have supplied reasons that went far beyond the lyrics.

“When I sing, my cup is filled to overflowing. I sing to express my gratitude,” soprano Alzira Lampropoulos said.

High school student Kim Rhyne sings because she gets the chance to perform pieces she enjoys, such as the music from “Les Misérables.” Jennifer Blanchard sings because she saw a flier for the chorale in a grocery store and because membership in the group has taken her all the way to Europe to perform.

Tom Smith sings because his wife and his mother-in-law were already in the chorale. Retired elementary school teacher Daisy Reynolds sings because “you can see we’re all having fun up there.”

For all of its 81 members, throughout its 20-year history, the Manassas Chorale has supplied hundreds upon hundreds of reasons to sing.

The Manassas Chorale recently celebrated its 20th anniversary. (by Cindy Laird./by Cindy Laird.)

The May 31 concert celebrated the 20th anniversary of the group, which has roughly quadrupled in size since its founding. Members recounted all the ways the chorus has grown. Once a come-as-you-are collection of singers in a church basement, its members now wear uniforms, pass tests including sight-reading and tone quality to join the group, and perform on the grand main stage at the Hylton Performing Arts Center.

More than 900 people attended the 20th-anniversary concert, which included a diverse selection of the chorale’s favorite pieces, including “How Lovely Is Thy Dwelling Place,” by Brahms; American standards; George M. Cohan classics; and a version of the rock band Toto’s “Africa.”

“We work very hard to just keep improving our skills,” said Rebecca Verner, director of the chorale. For the past 17 years, she has witnessed the increasing professionalism and size of the choir. She auditions each member every two years to ensure that their knowledge of music theory is sufficient to remain in the group. She has led her singers to Europe and to Carnegie Hall.

Verner said she takes pride in the age range of the members — from 16 years old to senior citizens.

“In an area like this, where so many people move in and out, you’re always going to have new people,” she said.

But some people stick around. Allan and Hannah Nixon are the sole members who have been part of the chorale for all of its 20 years.

Allan Nixon said he has enjoyed watching the group blossom. “Part of that growth has been that the chorale continued to serve in the community over those years,” he said, describing holiday concerts at nursing homes and affordable-housing developments. “We got a lot of support that way and became certainly well known in the community.”

Why does he sing?

“It just is stimulating and challenging to read new music, to then be part of a group that’s able to put it together,” he said. “And now that the group is sounding, I think, pretty good, that makes it that much more attractive.”