It’s Friday night in Southwest Washington, and Dick Smith is holding court.

The still-barrel-chested 74-year-old is on the dais at Westminster Presbyterian Church, addressing a sanctuary so full that people are left standing in the plaza outside the glass doors, waiting for a volunteer usher to hustle them into the rows of portable chairs. (There is no standing room.) But this is no church service or Bible study. It’s a concert, and Smith is leading the “congregation” in a singalong.

“We love our Friday jazz, love our Friday jazz,” they chant with the smiling Smith, a few off-key shouts and plenty of laughs thrown in. “Fried fish on Friday, fish and Friday jazz.” As he sings, trumpeter Thad Wilson and tenor saxophonist Paul Carr walk up behind him, playing their horns. Pianist Allyn Johnson, bassist James King and drummer Nasar Abadey swing merrily along in the back.

Behind them, on a large projection screen, is a slide show of photographs from performances past, featuring D.C. jazz greats, living and dead: Buck Hill, the saxophonist known as “the Wailin’ Mailman” for his day job as a postal worker. Butch Warren, the D.C. native who was once the house bassist at Blue Note Records. One slide features most of the band that’s playing now.

The concert commemorates the 20th anniversary of Jazz Night in D.C., a weekly Friday night program that Westminster initiated in January 1999. Smith, the executive director and curator, has partnered since that time with the church and its co-pastors, Brian and Ruth Hamilton, to bring the District’s top jazz talents in for three-hour stands of straight-ahead bop like this one, which features a string of time-tested standards like Dizzy Gillespie’s “A Night in Tunisia” and Nat Adderley’s “Work Song.”

Admission is an unbeatable $5 most weeks. For a few dollars more, true to Smith’s lyrics, Southwest Catering offers fried fish and jerk chicken from their buffet station in the basement.

But jazz and fish are only part of the story. “I come for the atmosphere,” says Bill Alfred, a longtime Southwest resident and attendee (and a musician who has been on Westminster’s bandstand a few times himself). “You can’t beat it. This is the place to be.”

“It’s a wonderful place,” agrees Gloria Turner, who regularly comes in from Fort Washington, Md. “To gather among friends and listen to the music is just absolutely a fabulous thing.”

“This is not a venue like other venues,” Smith explains. “We are a nonprofit organization that is about preserving this music, but also building a community. Building relationships, bringing people together.

“You might meet someone getting dinner, or on a break, and you mention that you need a plumber,” he adds. “They’ll say ‘I do plumbing!’ Or ‘My cousin does plumbing!’ You can meet the musicians, talk to them, arrange to hire them. So you’re getting referrals; you’re building relationships.

“So it’s more than just music, but it’s through the music that these things happen.”

Smith came to Washington 50 years ago in spectacular fashion: as a defensive back for the Redskins. But he was also an accomplished singer, and, almost as soon as he arrived, found in the jazz community a niche, one that outlasted his single season of pro football: working regularly with D.C. musical royalty the likes of Hill, pianist John Malachi and singer Ronnie Wells. In the 1970s he became a board member of Lettumplay, an organization that created new opportunities for jazz musicians as the clubs vanished.

By the late ’90s, Lettumplay’s footprint had gradually shrunk to an annual Martin Luther King Jr. Day celebration at Howard University. Then the Revs. Hamilton took over ministry at the venerable Westminster Presbyterian.

“Urban renewal really destroyed this place,” says Brian Hamilton, 61, reflecting on the government construction project that gutted, then redesigned and rebuilt the Southwest quadrant of the city in the 1950s. “The church almost died. It re-emerged as a very open, progressive congregation, but predominantly white and predominantly gay and lesbian.

“When we first moved here, it was known as ‘the gay church’ in Southwest. And that wasn’t a compliment. Certainly not down in the projects.”

Hamilton had no intention of putting the brakes on Westminster’s work, which, among other things, was at the vanguard of addressing the AIDS epidemic. On the other hand, he wouldn’t turn his back on the neighborhood that had hosted the church since 1853. His congregation agreed.

“So when we were getting to the point of, ‘How do we shift the conversation to include African American reality, history and culture?,’ the jazz thing was low-hanging fruit,” Hamilton says. Lou Taylor, a Westminster member who was plugged into the jazz scene, introduced him to Smith and drummer Earl Banks, his colleague at Lettumplay. (Banks died in 2012.)

They talked through most of 1998, finally deciding on the following January for their debut. There were ground rules. They had to keep admission low; artists would be paid, but the point was to be inclusive, and much of the neighborhood consisted of older African Americans of low or fixed income. It had to be early, so musicians could make later gigs at the more expensive clubs. And the music had to stick with the basics: bebop, ballads and blues, rooted in the late 1940s and ’50s.

“That’s the music a lot of our people came up with. But we also try to preserve this form of music because there’s a culture that goes with it,” Smith says. “The people, back in the time period [when this music was popular], they were smoother, warmer, with better relationships. That’s what the music of that time was about: being respectful. Being kind.”

They started slowly, averaging about 90 attendees a week for the first year. Then in February 2000, The Washington Post profiled the program. “People came out of the woodwork,” Hamilton says.

A cast of colorful characters developed. Lou Taylor and Earl Banks, both larger than life, were cornerstones. So was “Big Al” Swailes, who hosted a show on WPFW-FM radio. Connie Simmons, who may or may not have once sung with the legendary Art Tatum (“It was a story we embellished,” says Hamilton), took the stage every week until her death in 2006 to perform one of two songs, “All of Me” or “Stormy Weather,” to the audience’s consistent delight.

These folks let Smith and Hamilton know that their community-oriented mission was working. “We got an old-timer named Joe Jackson who grew up around here, before urban renewal,” Hamilton says. “He always says, ‘Man, this is the greatest thing. This is just like coming home again. Like it used to be when I was a kid.’ ”

As time passed, word spread, the neighborhood (and the city) changed, and many of the older regulars passed away, their places filled by a younger, more diverse audience and musicians. On the night of the anniversary concert, the crowd is still predominantly older and African American — but it’s dotted with young and middle-aged white, black, Asian and Latino people, all of them sitting, chatting and eating together, singing with Smith or hooting appreciatively at guest singer Sharon Carter’s effortless take on “I Didn’t Know What Time It Was,” or the lyrical solo Paul Carr contributes to it.

It’s “a great group of people, a very energetic and good crowd,” says Justin McCulloch, a 19-year-old student at George Washington University and jazz fan. “Pretty good music and a good vibe overall.” His friends Brianna Reynolds and Daniela Furtado, both 19, nod in agreement.

If anything, Smith and Hamilton say, the changes have made their community concept even more vital.

“The earth is shifting, so we do have to find ways that build community,” Smith says. “[New arrivals] are bringing different ways of thinking, and if you have that community concept of sharing and being respectful to each other, we’ll all be better off. Because other than that, you’re going to be fighting for survival, and not realizing, we’re all in this together.”

“This isn’t just art for art’s sake,” Hamilton adds. “This is art in service to the community. That’s important.”

If you go

Jazz Night in D.C.

Fridays at 6 p.m. This week’s scheduled performers include Marshall Keys (sax), Federico Peña (keyboard), Mark Prince (drums), Ameen Saleem (bass) and W. Allen Taylor (vocals).

Westminster Presbyterian Church, 400 I St. SW. $5.