Colbie Caillat has a confession: She does not consider herself a neurotic person.

Some might assume that any post-adolescent singer/songwriter with introspective leanings would harbor an at least occasionally tortured soul. But Caillat, 23, a blonde with a sweet, sunny smile, would beg to differ — as would anyone who checked out her breakthrough hit, "Bubbly," or most of the other tunes on her debut album, 2007's "Coco."

"The songs are optimistic and bright," Caillat says in her dressing room before a recent concert. "I grew up in Southern California and Hawai'i. The lifestyle was laid back, and I listened to mellow, positive music, like Bob Marley and Jack Johnson. So I think that's all inside me. I'm happy, and that gets expressed in my music."

Caillat and Johnson, 33, also from Hawai'i, are among the most prominent members of a new wave of troubadours luring fans of all ages into a peaceful, easy feeling.

The SoCal scene of the '70s, when artists such as the Eagles, Jackson Browne and Linda Ronstadt enjoyed some of their biggest hits, is one reference point. So is the Lilith Fair era of the '90s, when folk-based, mainly female artists such as Sarah McLachlan, Jewel and Paula Cole thrived at radio.

But more recent trends — from pre-millennial bubblegum pop to the production-driven hip-hop and rock of later years — favor flashier fare. The success of key exceptions such as John Mayer and Norah Jones may have helped launch other artists favored by the adult-alternative format. Still, guys and gals who sing softly and carry a guitar (or sit at a piano) have been considered long shots for commercial airplay.

That matters less as fans reach beyond radio in their search for new music. The advent of new media and marketing opportunities has provided these musicians with additional forums, from Web sites to TV shows to ad campaigns, that accommodate their gently infectious sound.

Though Caillat's father, Ken, produced Fleetwood Mac, Caillat's rise in the music industry was facilitated most directly by MySpace. She put some of her songs up about two years ago, and "after about six months, I had thousands of friends and fans, all adding my music to their pages," she says. "Because of that, I got a record deal."

Brett Dennen, 28, whose next album, "Hope for the Hopeless," arrives Oct. 21, is opening for Mayer this summer, along with Caillat. He says his "big break, aside from John Mayer taking me under his wing, was getting songs on "Grey's Anatomy," "Scrubs" and "American Idol." People heard me there when they didn't hear me on radio. That was my radio."

Advertisers, too, have given some of these artists "some of their initial and biggest exposure," says Blender magazine editor in chief Joe Levy. Hilton Hotels is using Dennen's "Blessed" in its commercials.

Similar success stories include Sara Bareilles, 28, whose "Love Song" surged on the pop charts after being featured in a Rhapsody ad last year, and French-Israeli singer Yael Naim, 29, who nabbed a top 10 hit in the USA after Apple used her single "New Soul" in its MacBook Air campaign.

Such collaborations may have once raised concerns about the corrupting influence of commerce on art, but no longer, says Levy. "We're well past the moment when audiences, young or old, are turned off by seeing music attached to television commercials, let alone television shows."

Moreover, the same virtues that attract advertisers make this music appealing to a multigenerational audience. "It's easy to listen to in the car, on the way to school or soccer practice or the mall," Levy says.

Rolling Stone contributing editor Anthony DeCurtis opines that the new singer-songwriters prove that young audiences have diverse tastes.

And they're surely loath to hear music pigeonholed. "Fans in their teens and 20s wouldn't identify a song they loved as 'mellow rock' or 'soft rock.' It's just not something they would be inclined to say," says Dennis Elsas, a veteran radio personality now at New York's WFUV-FM, which champions singer/songwriters.

Johnson is mostly amused by such terms. "People can call my music whatever they'd like," he shrugs. "It's not a bad thing to be called mellow."

"I have my painful moments like everyone else, but that's not the stuff I choose to share," says Jason Mraz, 31, whose latest album, "We Sing. We Dance. We Steal Things.," includes a duet with Caillat, "Lucky." "When we're happy, artists can be afraid to acknowledge what it is that makes us that way, or people will say it's cheesy. But I love that challenge. For me, music is meant for healing and inspiring."