"Exactly!" Sugarland lead singer Jennifer Nettles exclaims when asked if "Beyoncé to Bill Anderson" is a fair assessment of the duo's music.

"Exactly!" Sugarland lead singer Jennifer Nettles exclaims when asked if "Beyoncé to Bill Anderson" is a fair assessment of the duo's music. Not only has it performed the former's "Irreplaceable" in concert (a YouTube favorite), the pair co-wrote with country legend Anderson for its third Mercury Nashville album, "Love on the Inside," due July 22 (deluxe edition) and July 29 (regular).

Producer Byron Gallimore says the duo has an innate ability to blend its influences in a way that country fans find attractive. "Their experiences are pretty vast as far as the types of material that they know and can do, but the interesting thing about it is how country these guys are," he says. "It seems like whatever they do comes out country."

The duo has enjoyed as much country success as one can hope for if your name isn't Carrie Underwood. The act's 2005 debut, "Twice the Speed of Life," has tallied 2.5 million sales and spawned three top 10 Hot Country Songs hits. Second album "Enjoy the Ride" has sold 2.3 million copies and produced four top 10s, including the No. 1s "Want To" and "Settlin'."

"Love on the Inside" may be the purest Sugarland album yet, according to Nettles. "We're getting experience and we are also getting more comfortable in our own skin as writers, so musically on this record we went in and we really wanted to scale down," she says. "We didn't want everything to be super slick. We wanted it to be raw. We also had the luxury, because I was rested, of tracking everything live."

"They wanted to cut as much of this record as we could with less musicians and try to capture the magic in kind of a one-take performance, and that's pretty much what we did," Gallimore says. "It's got the growth that they we're trying to get."

For Universal Music Group Nashville chairman Luke Lewis, that kind of growth is key to building the Sugarland brand. "With the exception of her recognizable vocal style, they've made three pretty completely different-sounding albums," he says. "If artists keep making same-sounding records every time, you get to the point where there's no sense buying another one. You might as well just buy the single on iTunes."

Co-writers on the album include Bobby Pinson, who was responsible for "Want To," and Tim Owens, who co-wrote "Settlin'." Kenny Chesney guitarist Clayton Mitchell co-wrote the sultry "What I'd Give," and Anderson collaborated on the teen-angst tune "Joey." There's also a witty ode to oft-married singer/songwriter Steve Earle.

First single "All I Want to Do," which is No. 7 on Billboard's Hot Country Songs chart, is the duo's fastest-climbing yet. Response was immediate after the pair debuted the song in May at the Academy of Country Music Awards, according to country KMLE Phoenix music director Gwen Foster. "Listeners called with requests the next day and they haven't stopped. This song is connecting with country fans."

There's another reason for the song's rapid climb, according to Foster. "Sugarland has fast become a superstar act," she says. "Whatever Sugarland releases, country fans want it—and they want lots of it."

But rather than offer an expanded set six months or a year after the original release, Sugarland's label opted to release the fan pack before the new set. The expanded set includes "Life in a Northern Town," the Dream Academy hit that Sugarland, Little Big Town and Jake Owen performed on last year's CMT tour, and Matt Nathanson's "Come on Get Higher."

"We've gotten comfortable doing deluxe editions and fan editions after the fact," Universal Music Group Nashville executive VP of sales, marketing and new media Ben Kline says. "That really punishes the uber fan that comes out week one to buy the album because they ultimately have to go back and buy it again."

After opening for the likes of Chesney and headlining the CMT trek last fall, Sugarland will take labelmate Ashton Shepherd and rising star Kellie Pickler out this fall for a 25-city eastern U.S. tour.

Nettles says that her and Kristian Bush's prowess as singer/songwriters doesn't preclude them from being entertainers as well. "We really do try to explore the different elements of entertaining, of how you set a mood and capture an emotion with other elements besides the music, be it the exact lighting element for a song or taking a hard left and doing something ridiculous and crazy, like getting in a ball and crowd surfing," she says. "Why should you not be able to? I like to be able to add theater to the show."