On a Friday night, a quiet street in Brookline was winding down. But the lights remained on at the Brookline American Legion Post 11, a community center for veterans.

A small sign outside the building read, “POSTunderground: Live Jazz, Free Admission, Free Food.”

Through the bright foyer and down a flight of stairs, it was a different scene. Roughly 30 people, ranging from high school students to retirees, sat in chairs lining the walls and at tables in the center of the room. Plastic cups of beer and wrinkled junk food wrappers littered maroon tablecloths. On the walls, portraits of jazz greats were juxtaposed with American flags and photographs of veterans.

The Brookline American Legion Post 11 building on Sunday, June 21, 2026. The POSTunderground operates out of the veteran community center’s basement every Friday during alternating months of the year. (Artemisia Luk/WBUR)A sign outside the Brookline veterans’ post building reads, “POSTunderground: Every Friday 7:30-11:30 p.m. Live Jazz, Free Admission, Free Food.” (Artemisia Luk/WBUR)

“ As soon as you get in, you will feel like it’s a different world,” said Subhadeep Chowdhury of Cambridge.

Chowdhury, a regular at the club, was there with a small group. He had brought along his friend Namanjaya Khobragade, also of Cambridge, for the first time.

“Some of the younger people would like to go to a place which is louder or where people are dancing,” Khobragade said. “But this is more for people who like sitting and listening.”

All eyes and ears remained fixed on the opening quartet, Epistrophy, playing “Jagged Edges” by Troy Roberts. It was rare to catch anyone even whispering, or taking a sip of beer.

The audience at the POSTunderground jazz club claps after the band, The Jazz Situation, finishes their set on Friday, June 3, 2026. (Artemisia Luk/WBUR)Anthony Ghene and Amanda Xu of Fenway sit on the side of the POSTunderground basement during a break between sets. It’s their first time at the jazz club. (Artemisia Luk/WBUR)

Each musician took turns improvising. After the bassist plucked skillfully to the soft beat of the drummer’s cymbal, the audience clapped and cheered.

After the last song, a man with a long silver ponytail stepped onto the makeshift stage.

“ Welcome to Post Underground, where it’s always 3 a.m,” said John Purcell, the POSTunderground’s founder. Above him, a clock was fixed at the exact hour. “We’re not doing this for money, but we need money to do it,” he added. “We believe that music is a human right.”

POSTunderground’s John Purcell poses on a couch in Brookline American Legion Post 11. He rents the basement from the community center for local veterans. (Artemisia Luk/WBUR)

Purcell founded the POSTunderground in 2019 when he was a teacher at Brookline Music School. He wanted the club to feel like the jazz parties he’d throw in the 1970s and ‘80s, intimate affairs with no cover charge and free food.

The commander of the Brookline veterans post, Elmon Hendrickson, first reached out to Purcell because he knew that the building was underused. Older generations of veterans were aging out and membership was declining.

“ It was in really poor shape, and he made a big push to renovate it because he wanted to see it used by the community,” Purcell said. “That was his highest priority.”

When Purcell saw the building’s spacious basement with a built-in bar, he knew it would be a great music venue.

“Every jazz club on Earth should be in a basement,” Purcell explained. “The first thing you need to do when you enter a jazz club is go down the stairs.”

The built-in bar and the snack table at the back of the POSTunderground basement. (Artemisia Luk/WBUR)

At its beginnings, the POSTunderground attracted only a handful of audience members. But word spread quickly. Purcell set up a livestream room upstairs to help with overcrowding. He added two opening acts and additional Saturday night performances to accommodate a growing demand from musicians. Purcell retired from his teaching job at Brookline Music School in 2021 to devote his time fully to the POSTunderground.

Now, the POSTunderground jazz club is in full swing from 7:30 to 11 p.m. on Fridays and some Saturdays on alternating months of the year.

The POSTunderground house band, Hard Bop Cafe, performs for an audience on Friday, June 3, 2026. John Purcell, the POSTunderground founder, plays saxophone for the band. (Artemisia Luk/WBUR)

Greg Conroy, the drummer for the POSTunderground’s house band, has only missed one Friday night performance since 2019. He teaches percussion at Bridgewater State University and has been gigging in Boston with Purcell since the ’90s.

“The jazz scene in Boston is always in flux. It’s always changing,” said Conroy. “One day there’ll be a club that has music, and then it’ll be gone, and another one will pop up.”

In the past 30 years, Conroy has witnessed many beloved institutions shut down, like the Willow Jazz Club in Somerville, which shuttered in 1997, and Ryles Jazz Club in Cambridge, which closed in 2018.

With the rising cost of rent, it’s hard to keep any small music venue afloat. But the POSTunderground is more of a passion project than a profitable business. Purcell’s only goal is to break even with audience donations, which cover rent, the snacks, the bartender, and the $50 stipend for members of the house band.

A blue donation box at the POSTunderground, labeled “POSTbox.” Since there is no cover charge at the jazz club, donations cover the cost of rent, the house band, snacks and the bartender. (Artemisia Luk/WBUR)

Three days a week, the POSTunderground basement transforms into a music school — the “POSTunderground Institute.” There, Purcell teaches jazz to high school students and adults.

Sometimes, those same students open for the house band on Friday nights. Purcell also hosts a monthly Berklee/NEC night, featuring student musicians from the Berklee College of Music and New England Conservatory.

Carwen Simoneau of Roslindale, a freshman in high school who plays guitar, first started taking music lessons with Purcell at Brookline Music School. She normally doesn’t like solos, but appreciates how Purcell makes sure to fit in Grant Green’s “Idle Moments” during rehearsals, the one song she feels comfortable soloing.

“ It was recognizing, ‘Hey, this girl needs something to feel good about,’” said Simoneau.

Students Ella Xhoja on saxophone and Carwen  Simoneau on guitar during a lesson with POSTunderground founder and instructor John Purcell on Sunday, June 21, 2026. Three days a week, Purcell teaches jazz in the POSTUnderground basement. (Artemisia Luk/WBUR)POSTunderground Institute students practice their instruments in the empty basement of the Brookline veterans’ post on Sunday, June 21, 2026. (Artemisia Luk/WBUR)

Purcell is gradually expanding the lineup of musicians. He plans to add more Saturday shows to accommodate bands who can’t fit into the regular rotation.

“It really is a community, and he is about community,” said Conroy. “It really has brought a lot to the scene.”

Purcell believes the POSTunderground draws a self-selecting group of music lovers.

“The audience is here for the music,” he said. “And the musicians are here to play for that audience.”

In this hidden basement in Brookline, Purcell is carving out a scene for Boston’s jazz musicians — in this generation, and the next.

The POSTunderground is open every Friday in July. Berklee/NEC Night is on Saturday, July 11. The POSTunderground summer classes will culminate in two performances on Sunday, July 26.