Put simply, Hanson have grown up.

Isaac, the oldest of the three Tulsa, Okla., brothers whose song MMMBop clogged the airways for much of 1997, is 23. The youngest, Zac, is a legal 18. And middle-brother lead singer Taylor, 20, is a married father.

But perhaps the biggest way in which they've grown up is the way they've taken control of their career.

After disputes with their record label, Island/Def Jam, left them without a release for four years, Hanson left to form their own 3CG label to release Underneath.

They seem to have made the right decision. The album debuted in April as the No. 1 independent record in the Unnited States and No. 25 on Billboard's Top 200, making it one of the most successful self-released albums of all time. Its single, Penny and Me, debuted at No. 2.

While the numbers for Underneath aren't quite those of MMMBop and the album Middle of Nowhere, which sold 8 million copies worldwide, the new release clearly has re-energized Hanson's career.

"The fans have really been waiting a long time for this music," says Isaac in a telephone interview from Kentucky. "And it's really beginning to pick up steam among the fan base and continuing to spread. It's really exciting."

In fact, with seven years having elapsed since MMMBop was released, Isaac says many younger fans aren't even familiar with it.

"It's amazing, because in shows we get as much of a response from Penny and Me as we do from MMMBop," he says.

That would have seemed unthinkable following the release of Middle of Nowhere.

With grunge then dominating music in 1997, MMMBop got three Grammy nominations and was followed by two more Top 10 singles, Where's the Love and I Will Come to You. Rolling Stone magazine chose Middle of Nowhere among its Essential Albums of the '90s.

And the Hanson boys, then just 16, 13 and 11, were credited with helping spawn the late-'90s wave of boy bands such as 'N Sync and Backstreet Boys.

But the band's follow-up, 2000's This Time Around, sold only 1 million and had no hits.

And when it came time to record Underneath, Hanson and Island Records had "creative differences," Isaac says.

"We really felt like it was just the right thing to do to move on."

Starting their own record label allowed them to choose producers -- among them Greg Wells (Michelle Branch), Bob Marlette (Marilyn Manson), John Shanks (Sheryl Crow) and Danny Kortchmar (Don Henley, Billy Joel), who co-produced Penny and Me -- and distributors, Isaac says.

"There's nothing better than being in control of the music that you're making," he says. "The exciting thing is you're able to find the people who really understand the music and are really passionate about it."

Penny and Me gave the group the right single to push the finished product, Isaac says.

"You try to write catchy songs, and when you stumble across songs that you really feel like are the most easily palatable to people -- there are just certain songs that kind of stick out, and Penny and Me was definitely one of them," he says. "There's something about the chorus, there's something about just the melody of the song that definitely stood out to us to where we felt like it was the right song to be the first single."

MMMBop was a song like that, Isaac says. And while it was played enough to make anyone tired of it, he says "MMMBop is definitely still very much a song that we are very proud of.

"I'm very proud of all the stuff we've done, and we continue to pull from all of the repertoire every single night. It's all still a part of who we are."