When Avril Lavigne released album No. 2 in 2004, the spunky teen pop star announced to the world that she was growing up. Gone were the baggy pants and skater-chick image that first earned Lavigne the media-christened nickname of "the anti-Britney."

On that year's "Under My Skin," punky anthems like "Sk8er Boi" were replaced largely with grammatically correct, midtempo teen-angst rockers. The album was released a few months shy of Lavigne's 20th birthday, and the black and white, goth-like imagery made it clear that Lavigne was dealing with some intense late-teen issues.

Today, Lavigne is done with all that.

On April 17, she will release her third album, "Best Damn Thing," on RCA, and the mood is decidedly lighter. Ask Lavigne about forthcoming single "Girlfriend," and Lavigne doesn't so much as answer as break into song. Simply mention the tune to Lavigne in an interview, and she perks up and starts singing the chorus, air punches and all.

Lavigne has never been nearly as animated as she is on "Best Damn Thing," at least from the six songs her management firm, Nettwerk, allowed press to hear. "Contagious" is her hardest-rocking song to date, and features Blink-182's Travis Barker on drums. Yet elsewhere, the album moves like an arena-rock party, with the title track and "I Can Do Better" built for fan sing-alongs, with the latter even sporting some dancey rhythms to go along iwth its pop-punk guitars.

"I was just so over writing such serious songs," Lavigne says. "Even though they really weren't that serious, I went through a little dark phase when I was 18 and wrote 'Under My Skin.' But I grew out of that. Lyrically, I didn't know where I was going to go on this record. I totally did not even think about it. I had no theme. I was thinking more about the music and the vibe."

Read more about the vibe of "Best Damn Thing," the album's multiplatform marketing component, Lavigne's changing audience and more.