New York ? The Black Eyed Peas spent years languishing in hip-hop’s underground before they found the formula to vault them into the mainstream – accessible pop melodies, star collaborations, marketing tie-ins and a sexy young thing to belt out catchy choruses.

That mix made their 2003 album “Elephunk” their big breakthrough. Their first two albums failed to sell 500,000 copies combined. But “Elephunk” – which featured the Grammy-nominated anthems “Where Is The Love” with Justin Timberlake and “Let’s Get It Started,” which became the National Basketball Assn.’s playoff anthem – went multiplatinum and made them and their music ubiquitous.

Still, there are plenty of early Peas-heads who remain disgruntled about the group’s leap to the pop world.

But go ahead and call them sellouts. Lead lyricist will.i.am doesn’t mind.

“It’s cool,” he says. “It makes me feel good because that means they really liked our first record.”

And then the group breaks into uproarious laughter.

The Black Eyed Peas have plenty to be merry about these days. Coming off a Grammy this year and the success of “Elephunk” (2.7 million copies sold), the foursome should prove they aren’t a flash in the pan with their latest album, “Monkey Business.” The disc, which again features Timberlake, along with the Godfather of Soul James Brown, sold 291,000 copies in its first week of release, according to figures released Wednesday. And the funky first single from the album, “Don’t Phunk With My Heart,” is already a Billboard top 10 hit.

The Black Eyed Peas are photographed on the roof of Sony Studios in New York on May 2. From left are Taboo (Jaime Gomez), Fergie (Stacey Ferguson), will.i.am (Will Adams) and apl.de.ap (Allan Pineda).

Amy Doyle, MTV’s vice president of music and talent programming, says the key to the Black Eyed Peas’ success is their ability to “straddle a wide audience … their music is not polarizing.”

“It’s really all about the catchy songs that they write that get stuck inside everybody’s head as well as a real vibrant live performance,” she added. “And they always deliver really good videos too.”

The Los Angles-based group, which initially started out years ago as the trio of will.i.am, apl.de.ap and Taboo, first came onto the scene as an effervescent band that melded eclectic hip-hop beats with lyrics that were sometimes socially relevant, sometimes irreverent, but definitely apart from the sex and violence that permeates much of rap and hip-hop.

Critics loved it, and they had a strong following.

But their debut CD, 1998’s “Back To Front,” had only modest success. And the weak response to the follow-up, “Bridging the Gap,” left them feeling particularly defeated, and they fell into destructive habits.

Eventually, the band decided to put all their focus into “Elephunk,” which they saw as potentially their last album.

Besides getting themselves together, they also decided to tinker with their sound. A previous female vocalist they used on tracks had left, so they found Fergie – a former member of Wild Orchid, which had modest success in the ’90s.

Joining three guys who had been together for years wasn’t easy for Fergie.

“It was like a gradual progression for me on stage, because they had been together for years. I’m coming onto the stage, not really knowing where I fit in. So I kind of had to sit back and watch and find my niche in the band,” she says.