Most musicians will tell you that developing a signature style is an ongoing evolution. As such, sometimes looking back over a body of work can be an amusing and insightful exercise in getting from Point A to Point B to Point Wherever. But don't expect the members of Lake Street Dive to spend a lot of time pondering their own gestation.

The band is one of the headline acts at the Rhythm and Roots Festival taking place Friday through Sunday at Ninigret Park in Charlestown, R.I. Other acts include The Mavericks, Los Lobos, Marcia Ball, Royal Southern Brotherhood, Keb' Mo', Steve Riley & the Mamou Playboys, and many more established and up-and-coming Americana artists.

As always, there will be plenty of workshops, dance instruction — and indigenous food and drink to provide fuel for the fun.

Lake Street Dive, performing at 9:45 p.m. Friday, is a perfect and inspired fit to the lineup. It's a wonderfully distinctive quartet whose sound was rooted in country swing — if, that is, Cole Porter and Dinah Washington had joined Milton Brown's Brownies. Over time, that formula has grown to include space-pop styles from Difford and Tilbrook to Phish, all percolating in a vitally exciting live presentation around the maple-syrup-with-Tabasco vocals of Rachael Price. Bassist Bridget Kearney, drummer Mike Calabrese and guitarist/trumpeter Mike "McDuck" Olson contribute extensive instrumental interplay — which is not that surprising since they all met at the New England Conservatory.

"I think we've honed in on a sound over the years that's sort of the 'Lake Street Dive Sound,'" Kearney says. "If you listen to our first album — and you can't because we don't sell it anymore because it's terrible — the songs are all over the place. Now, we've learned what type of songs we do best and are focused more towards that."

Their rapidly escalating fan algorithm would probably suggest Kearney's being a bit harsh in her early-days assessment. But it's also true that their fourth album, last year's "Bad Self Portraits," is the record that has moved Lake Street Dive into mainstream popularity and headliner status.

All four band members write, and the rehearsal room, where the music is examined and jammed to and nurtured, has become a truly alchemical spot.

"We don't want to put any limitations on what we can do, and we don't want to keep writing the same songs over and over," Kearney says. "When we start writing new material, we cast the net wide. Pretty much anything that any of us bring in will be given a chance ...

"Our development process has always been trial and error, so to get better and find new ways that we can work together, we have to keep trying things and making mistakes. It's fun and terrifying!"

Given Lake Street Dive's collective will and creative attitude, it's also true that they never assumed success.

"We've quite drastically exceeded our original expectations and goals for what the band could achieve," Kearney says. "It's a real thrill to walk out to bigger and bigger groups of people and see them all singing along to our songs."

But the group still firmly believes in the hunger and inspiration that drove them from the first.

Kearney says, "We've challenged ourselves to try and maintain some of that dive bar aesthetic and visceral energy in our shows — even as the stages get bigger. We want every person in the venue to fell like we're personally playing to them."

And while they're enjoying such opportunities, Kearney says the band loves participating in events like Rhythm and Roots.

"Festivals are where you get to introduce yourself to new fans and be introduced to new bands that you might love. There are so many great acts that are going to be at this festival that I can't wait to see. That's a big bonus to our job," she says.

Rhythm and Roots Festival,4 p.m.-midnight Fri., noon-midnight Sat., 1 p.m.-midnight Sun.;  $50 Fri., $70 Sat. and Sun.; 1-888-855-6940, rhythmandroots.com.