Fall Out Boy: This is hardcore

Last year, Fall Out Boy's bassist Pete Wentz attempted suicide; now the band are punk-pop gods

They have some of the longest song titles in pop history - "Our Lawyer Made Us Change the Name of This Song So We Wouldn't Get Sued" and "I Slept with Someone in Fall Out Boy and All I Got Was This Stupid Song Written about Me". Their second album, From Under the Cork Tree, released a year ago, is nearing triple-platinum status and has sold more than 2.5 million copies in the US alone. For angst-ridden American teenagers, they are the gods of America's newest punk-pop revolution. Their new single, "Dance, Dance", is at No 8 in the UK chart this week, and they are NME cover stars. And Fall Out Boy are heading to Britain next month.

Pete Wentz, 26, is the band's figurehead, their bassist and lyricist but not their singer. He wears black eyeliner and has chipped black polish on his nails and is currently lying in bed in a hotel room in Florida, having not yet got up although it is lunchtime. The rest of the band are also asleep and scattered around the hotel - the shy singer, Patrick Stump, 21, the vegan drummer, Andy Hurley, 25, and the hyperactive guitarist, Joe Trohman, 21. Pop-punk's new superstars are currently in the middle of an arena tour in the US playing to an average of 10,000 kids a night. They need to sleep in.

What quite has driven American teenagers wild about Fall Out Boy for the last year has as much to do with the need to connect to Wentz's deeply personal, introspective lyrics about self-doubt and self-loathing, as it is to their hardcore punk sound with pop sensibility. "I think - especially in America - that people don't realise it's OK to feel down and sad sometimes. It is part of the cycle of feeling OK. If you never feel sad, how do you know if you are OK?" says Wentz. "There is an honesty in our music and I think people appreciate it. We have never dumbed down to teenagers by writing songs about being in high school and having your locker jammed. We have been thoroughly honest about what out intentions are. We have always written what we are really feeling. We have always had the respect that they are going to figure out these songs for themselves and come up with their own interpretations."

Wentz's online journal reads: "Sometimes it's hard to look in the mirror and feel OK with the person looking back." (Wentz has been in therapy for a while.) He even offers help to fans with issues such as bereavement and getting dumped via the band's website.

But the multi-tasking Wentz is so much more than an agony aunt. He is also a pop-punk entrepreneur, pushing Fall Out Boy unashamedly towards media brand, rather than pop band. "We are just ordinary boys in an extraordinary position," says Wentz. "That can be inspiring for other ordinary people. If there is any revolution we are inspiring it is that we have taken our own fate into our own hands. We are total control freaks."

So much so that Wentz has created a record label, Decaydance Records (notable signings are Panic! At The Disco and The Academy Is...), a clothing line, Clandestine Clothing, and a film production company, Bartskull Films - "We write our own video treatments and partially direct them."

Wentz has even self-published a graphic novel, a dark, twisted tale called The Boy With the Thorn In His Side (named after a Smiths song) and another 200-page book, Rainy Day Kids, is on its way. "It's a bit like [Nikolai Gogol's] Diary Of a Madman," Wentz says. "My inspiration and my ideas don't begin and end at the beginning and the ending of a song. It is too limiting." It is no wonder that the singer, Stump, said of Wentz: "It scares me sometimes, watching him. The two seconds you're not with that dude he's made 30 decisions that are going to affect us for the rest of the year."

Then there is the band's MySpace page, buzzing with more than 750,000 " friends" living in the band's online, virtual community. "In an age when people can so easily click a button and download it's not good enough to just give somebody a song," says Wentz.

Suffering from depression - "black clouds" - he has described his moods as "oil and water and they never mix together right". In February last year, just as the band were recording their breakthrough album, Wentz went into emotional meltdown. In the Best Buy parking lot in Chicago, full of pain - "my head was racing with self doubt and negative thoughts" - he swallowed a handful of Ativan anxiety pills in an act that he calls "hypermedicating".

He recalls: "I just wanted to have my head shut up. I didn't really think about whether I slept or died." About this dark time in his life, he says: "It was overwhelming. I was either totally anxious or totally depressed. It is particularly overwhelming when you are on the cusp of doing something very big and thinking that it will be a big flop. I was racked with self-doubt."

He had been obsessed for a while with the tsunami and his own mortality. He withdrew from the rest of the band, only appearing to hand them his lyrics. But after the near-death episode - he had his stomach pumped - Wentz moved back into his parents' house in the posh Chicago suburb of Wilmette ("A place straight out of one of those Eighties movies like The Breakfast Club," he says), leaving the rest of the band to tour the UK in February 2005 without him.

"It's really boring there. Not a whole lot going on. Mom's [a school administrator] in the kitchen baking stuff, and dad's [a lawyer] off at work. It's very non-exceptional." Wentz says that sleeping in the bedroom that he grew up in made him "more sensitive to adolescent angst".

He has admitted to a fascination with the suicides of Elliott Smith and Joy Division's Ian Curtis. But there is nothing fake about this dark period of his life, just stark honesty. He says the depression wasn't caused by any particular trauma in his childhood, which was "pretty mundane - the mundane and the ordinary can be very depressing. Very, very depressing," he says. "I find that writing songs is cathartic. The problem is I can get addicted to that feeling that you get from writing a song that can get unhealthy because you are relying on it."

He does therapy even when he is on tour. "It helps just to be able to give what you are thinking out. Keeping it in your own head is not always the best thing. When I'm home I do it most days, but when I'm on the road I do it on the phone."

The band - all from Chicago - formed in 2001, taking their name from Bart Simpson's favourite superhero, Radioactive Man's sidekick. They had all been involved in Chicago's hardcore scene, playing in a handful of bands, when they met. The first album they made together, Fall Out Boy's Evening Out With Your Girlfriend, was released by the California indie label Uprising.

They were then signed by John Janick, co-owner of the Florida indie label Fueled by Ramen, and the band released their first full-length album, Take This to Your Grave in 2003, inspired by Wentz's break-up with his girlfriend (who has since become famous in her own right for her presence in the album's lyrics). Island Records snapped them up later that year. Having released From under the Cork Tree, the band won the MTV2 Video Music Award in Miami in August (beating The Killers). The rapper Jay-Z heralded the band as "a movement", and took his girlfriend, Beyoncé Knowles, to a New York show last year.

The band's breakthrough single, "Sugar, We're Goin' Down", reached No 8 in the US Billboard Hot 100 in September 2005, and in the UK chart in February this year. The accompanying video told the story of a boy with a pair of antlers on his head who finds love with a girl who sees past the antlers to the real him.

Wentz doesn't really care what his band is labelled as: "I think that people lay whatever labels they want on everything because they just need to have that in order to understand the world. I want people to love us or hate us because of our music not because of the label." But he describes his own new genre of music as "softcore": hardcore punk mixed with pop sensibility. "I think the interesting thing is that we are all hardcore kids that are writing pop music," says Wentz. "A lot of people take it the other way and are pop kids trying to write heavier music. It gives us a different style because at our core we are always hardcore. That aspect is always going to be evident in the music. We are hardcore kids that couldn't quite cut it as hardcore kids."

Stump - the singer - admits to being "horribly uncomfortable" about being the frontman. However, Wentz says it is "a refreshing change " from other American punk and emo bands - "He's got this wide, big, soulful voice that I don't think you hear much of in this type of music, which is usually more nasal. He's not afraid of his vocal range. He sings as if it comes out through his diaphragm, not through his nose."

Although Stump can write lyrics, "but I cannot write Fall Out Boy Lyrics ", it is his job to put Wentz's lyrics to music. Wentz's lyrics on the latest album, he says, are much "more introspective" than the previous album. "Take This To Your Grave was very reactionary," says Wentz. "It was like this person does this to you. But part of growing up is understanding that if you end up in the same situation over and over again you probably have to examine your own self and wonder whether that's one of the reasons that you have ended up in the same situation repeatedly. This time the lyrics were more about the anxiety and depression that goes along with looking at your own life."

His favourite song on Elliott Smith's XO is about "who you are versus what you want to be". The Fall Out Boy song "I've Got a Dark Alley and a Bad Idea that Says You Should Shut Your Mouth", he says, is about "looking in the mirror and not feeling safe in your own skin".

Did he ever imagine that he would be in one of America's biggest bands of the moment? "You dream and hope that you could do something like that, but I didn't imagine that it would happen," says Wentz. "I looked at bands like Guns N' Roses and I wanted to be that guy. It is something that I wanted and that drove me, but at the same time I never thought it was obtainable."

How has the band's success changed his life? "We have more opportunities now, but it has made me more guarded as a person. I don't trust people as much as I used to." Wentz is looking forward to coming to the UK, "where it hasn't exploded as much as it has over here. Because the UK are about six months behind, it's like watching it all happen again." How is the band coping with fame? "In the vacuum away from all the press and away from all that camera flashing, we are still just best friends and that's how it will continue to be, I hope, all the way into the future."

'Dance, Dance' is out now on Mercury; Fall Out Boy tour the UK in May (see www.falloutboyrock.com for details)