The Free Radicals are one of Houston’s most beloved and iconic bands, and for good reason. Since 1996, front man and founding member Nick Cooper has provided Houston concertgoers with an eclectic and lively mix of jazz, ska and reggae featuring a revolving door of talented musicians.

“We enjoy playing uplifting music,” Cooper says of his band. “We show up to celebrate.”

Seven musicians grace the stage for any given performance; the marching band consists of five members; and for weddings, funerals, parties and street protests, a total of 15 musicians are present.

“We are ready to book your funeral,” Cooper says. “Just call when you know the date.”

More than 50 musicians have made appearances on the Radicals' records, and while band members may come and go, Cooper says material is constantly being written and rewritten.

“Some songs squeak in just under the wire, being written and recorded just before we send the CD off to be pressed,” he says. “Others are in the works for a decade before they feel ready to record.”

This weekend, the Free Radicals will release their sixth studio album, Outside the Comfort Zone, Saturday at Last Concert Cafe.

Originally titled The Legals Have a Lunch, the band's new album is “pretty thick” by Cooper’s own admission, with even its simpler tracks employing more musicians than previous recordings. So much so that even naming the record proved to be a difficult task.

“Choosing the album title was a frustratingly democratic process,” Cooper says. “We knew that the cover of the album was going to be a white family eating obliviously in a diner while, outside, people of color were being frisked and rounded up, but we debated what to call it for weeks.”

Another name considered for the album was Post Racial Society – a nod to the idea that racial tensions in the U.S. were a thing of the past in the post-Obama era – but the band decided that was too obscure of a reference.

“There is no essay, analysis or metaphor for the nightmare planet we are constructing,” Cooper says. “When we even peek outside our comfort zones we try to inhabit, the only honest response is a scream.”

Fittingly, the group’s new album features a song called “Screaming,” which showcases horns that sound like a warbling shriek, providing an outlet for the band’s frustration with the past year’s happenings.

His generally critical outlook on the U.S. notwithstanding, Cooper says he was proud of his hometown and the unity its inhabitants displayed following the damage brought by the recent flooding.

“Harvey showed us that individual Houstonians kick the ass of any recovery professionals like the Red Cross when it comes to individuals coming together to help others in trouble,” Cooper says. “Free Radicals has known that for years, because we support, volunteer and do fundraisers for grassroots groups that are taking care of Houston with little to no budget.”

But that doesn’t mean he thinks the Bayou City is perfect. Far from it.

“Regardless of all the cool organizations that exist, real estate and petrochemical interests run the show here,” he says. “They're killing people, oppressing the poor and making our city a dump.”

Citing environmental concerns – water, soil and air toxins coupled with radioactive drinking water – Cooper criticizes Mayor Sylvester Turner and the ostensibly progressive leaders who preceded him.

“The people who are poisoning indigenous children across the global South belong in jail, but in Houston, they are powerful, respected figures,” he says. “We love you, Houston, but shit is pretty doomsday around here.”

Also featured on the new album is a song called “Doomsday Clock,” a ska tune featuring trombone, trumpet, tenor and guitar solos. Like many of the songs on the new record, it's much more upbeat than its name suggests.

“We try to stand against oppression and to provide a beat,” Cooper says.

With song titles like “Audacity of Drones,” “Scrapple from the DAPL” and “Ambush ICE,” strangers to the Free Radicals might think their show has an overbearing political slant, but Cooper says that isn’t the case.

“Our music is instrumental, and we don't give any lectures from the stage,” he says. “Our titles and cover art may be dark and cynical, but our music exists only to heal.”

From celebrating the lives of fallen brethren to espousing the importance of Houston’s vibrant refugee population, the Free Radicals rejoice just as much as, if not more than, they criticize. Their live shows are legendary in Houston, and the fire in Cooper’s belly burns with as much fervor as it did 21 years ago, when the band first formed.

And through it all, he maintains a dry wit. When asked if he has a favorite track on Outside the Comfort Zone, Cooper responds, “We love all our children equally.”

Free Radicals and special guests Soul Creatures and Bayou City Funk celebrate the release of Outside the Comfort Zone Saturday, September 23, at Last Concert Cafe, 1510 Nance. Doors open at 9 p.m.