Rhyme wave

"It's not about tolerance; it's about respect!" yells the figure at the front, to a medley of stamping feet and whistles. For the past few minutes, this tiny, elfin creature in leather trousers and a diamante-studded top has been whipping us into a frenzy of enthusiasm, training us, in fact, in the art of "bigging-up". "That's a little bit better," she announces. "Now let's see what you can do."

"It's not about tolerance; it's about respect!" yells the figure at the front, to a medley of stamping feet and whistles. For the past few minutes, this tiny, elfin creature in leather trousers and a diamante-studded top has been whipping us into a frenzy of enthusiasm, training us, in fact, in the art of "bigging-up". "That's a little bit better," she announces. "Now let's see what you can do."

In the seats around me, children are wriggling. They're excited, but they're also scared. When the MC yells out their names, they'll be up there, too. This is the quarter-final of the Poetry Society's annual Respect Slam, and half the audience is taking part. If they make it to the finals, they get to perform at the Mayor of London's Respect festival in Victoria Park, east London, in July. "Dizzee Rascal can't be here tonight, but he's going to be here for the finals," she announces, with a huge grin. "Benjamin Zephaniah's sent a message of support, and so has Lady Sovereign."

We listen to the messages, we whistle at the DJ (so confidently gorgeous that when I ask him later where he lives, he thinks I'm trying to pick him up) and then we pick the judges. For this is a democratic affair. A helper hands the MC a large basket. "If your number's up, you're a judge," she yells. "You are the voice of the audience." Numbers are called, bingo-style, and sheepish hands go up. All adults - mums, dads, teachers and the odd social worker - have been handed tickets on the way in, and now they're going to determine the fates of the little darlings on stage. Not so little, actually: some of them are hulking teenagers who could just as well be boxers as budding poets. "You judge them on the quality of the writing," she shouts, punching the air with each new item on the list, "the originality of the writing, the strength of the performance - and how they address the theme of respect."

Still in its infancy in this country, the poetry slam has been a feature of the American cultural landscape for 20 years. It started when a Chicago construction worker, Marc Smith, decided to transform the traditional "open mic" poetry night into a poetry cabaret. On regular Sunday nights at the Get Me High Lounge, he introduced a new style of competitive poetry event. It soon spread across the US and into New York, most notably at the (extremely lively) Nuyorican Poets Café, on New York's Lower East Side.

The Poetry Society's version started nearly three years ago with a call from the Greater London Assembly. Did the society want to run a London-wide poetry competition for schoolchildren, as part of the Mayor's annual Respect festival? No, it didn't. I know, because it was me who took the call. As the director of the society at that time, I'd seen enough sacks of doggerel pouring into the office to keep us going for quite a while. We were already running the National Poetry Competition and the Foyle Young Poets of the Year award, and I wasn't sure that we could stomach any more. "How about a poetry slam?" I suggested brightly.

Six months later, we were at the Oval House theatre, watching one group after another troop on to the stage and entrance us. Off stage, some were a little surly, unused to shining in - or out of - the school arena. On stage, shoulders went back and faces lit up. The winner that year was Daniel Peck, a tiny, blond 12-year-old, who wowed the audiences at the Oval and at Chats Palace, in Hackney, and wowed them again at the showcase event in Victoria Park. His fellow finalist Anthony Anaxagorou, a smooth-looking London Cypriot, went on to perform his work on radio and TV.

It was Joelle Taylor, tonight's leather-clad MC, who played the biggest part in putting flesh on the bones of the dream. A performance poet and education officer at the Poetry Society, she worked with Jules Mann, now the society's director, on the daunting task of sending details of the slam to every London school and co-ordinating the semi-chaos that ensued. That first year, there was one quarter-final and one semi as well as the festival final. Last year there were two quarter-finals, and this year there are four, including tonight's, at the ICA. For Taylor, co-ordinating the slam, MCing all six events and running the workshops for the finalists is now practically a full-time job.

"First up", Taylor yells, "are some veterans from last year's slam. Please big it up for Jean Shyaka, Henry Nwasokwa, Anthony Idebi and Adedayo Onakoya." Like most of tonight's contenders, they're wearing huge, baggy tracksuits, baseball caps and big, chunky gold chains. They kiss the microphones and start emitting the extraordinary mix of orally produced drum and bass sounds known in rap as the "beat box". And then they launch into their poem: an impressive polyphonic rap performed at breakneck speed and with considerable panache. The judges, meanly, give them only a six.

Rap features heavily in tonight's programme, but there are non-rap poems, too. "Tonight," says Jordan Rochester, whose arrival on the stage triggers a medley of wild calls and shrieks, "I'm going to do something called 'Dream'. I consider myself a rapper and a lyricist, but if I rap I'm going to be limited to the rhythm..." The poem he reads is raw but strangely touching. When the judges present their verdict - a seven - his vocal schoolmates yell out their disappointment.

In the interval, I talk to Saverio Brancaccio, another veteran of last year, who has been MCing since he was nine. His family are Italian but he speaks with a mock-Jamaican accent. I meet Anu "Madnessity" Sawhney, a 16-year-old with Bollywood-star looks, who has been doing radio ads for McDonald's. And Jozef Korbell, a redhead in a red tracksuit and member of The Rappateers. A large white woman brushes past us and plants a huge kiss on Jozef's freckled forehead. "He's my baby," she smiles. "I'm so proud of him."

In the second half, Taylor returns to the stage looking a bit frazzled. "If there's a disagreement," she instructs us, "write a poem about it. There's been an incident," she adds sternly, "and the people involved have been asked to leave." There has, I find out later, been a sudden outbreak of disrespect in the Gents. It had something to do with low scores, and the people involved didn't just write poems in protest.

Still, there's plenty of respect on the stage. James Lydon, a spiky-haired 16-year-old in a black shirt and red tie, kicks off with his poem "Medalman", a touching tribute to his grandfather. He's followed by a group of seven rappers called The Southsiders. They're 12 but look younger, and the one who steps out to make a speech, large-eyed and sweet-faced, like an Ethiopian Jesus on a Christmas card, looks about eight. "Respect is important, because without respect our society would crumble and the world would be a dreadful place," he tells us with a radiant smile.

The Southsiders are great, as are The Rappateers, and so is Baby Isako, whose poetic account of the refugee experience provokes rapturous applause. As the evening goes on, the scores go up. In spite of the unfortunate disappearance of one or two of the performers, the hall crackles with energy. By the end of the evening, when they all troop back on stage for a final, sheepish bow, we're all shrieking and yelling.

A week later, I'm back with The Southsiders at their school in Battersea to observe their reward: a workshop with Crisis, a beautiful young performance poet in baggy jeans and a tie-dye kaftan. "Be casual! Be cool!" the boys hiss to one another when they hear that I'm a journalist. "Miss!" they say, gratifiyingly, "Miss, are we going to be famous?"

We start off outside. Crisis does a poem of his own first: a beguiling mix of singing, rap and ragga. Then the boys launch into their rap again: "Respect, respect, respect is the key./ I give it to you, and you give it to me." By the end of the afternoon, I feel I could do it myself. It starts off with mention of "a very smart fella" called Nelson Mandela and moves on to guns, slaves, R&B and the need for freedom. In an earlier version, their teacher, Miss Wootton, tells me, one of the boys included the line: "Your mum's too ugly to get dates." It was swiftly, and tactfully, removed.

Crisis offers advice on their performance: they could sharpen up their movements, the harmonising and the beat box, but his overall verdict is "fantastic". The bell rings, and we move inside. On the walls of the classroom are notices: "Txt messg read now: DON'T 4GET UR HW", "DON'T BE BOYED" and "GET NEEKY!" I have to ask for translations. "Do you think we have a chance?" the boys ask after about their 10th performance. "The thing is, you're all winners anyway," Crisis says. The boys look disgruntled. That's not the kind of winning they want.

"In one way it's our favourite project," Jules Mann says later, over a drink. "It's so raw and heartwarming, and you feel you get the origins of a poem from these kids who often haven't had much of a chance to express themselves in any other way. Then you take it from there to help them work on the craft. I've just come from the launch of this year's Respect festival," she adds, "and it's clearly one of the GLA's favourite projects, too." With Ken on side, it looks likely to prosper. Just don't bring your cars.

The Respect festival is at Victoria Park, London E2, on 17 July