"A soccer ball has a lot of power," says DeAndre Harrison, sitting in the sunshine during a break from the action at the Football for Hope Festival. Harrison is here in Johannesburg as a youth leader for Team USA, one of 32 sides from disadvantaged communities across the world taking part in this festival of education, culture and football.

The 20-year-old American knows better than most the sport's capacity to serve as a tool for education having become involved with the Soccer in the Streets project in his native Atlanta when he was a young boy. Soccer in the Streets is one of three organisations that form the US delegation – together with the Starfinder Foundation and Urban Soccer Collaborative – at the event in the Alexandra township and, in his own words, "it gave me an opportunity to change my life". He recalls: "When I was 11 they came to my neighbourhood and they started a programme there. Soccer in the Streets basically uses soccer to teach life skills. We teach people how to be employable adults."

The project, which started in 1989, works with around 450 youngsters, primarily from the African-American and Hispanic communities in Atlanta. To develop their skills, executive director Jill Robbins explains, Soccer in the Streets will "train them as referees, as coaches, as administrators. They even get to organise events." Now mentoring Team USA's young players Harrison is testament to that. As he says of his organisation's work: "It is called the school of life and most of it is done on the field."

It is called the school of life and most of it is done on the field

DeAndre Harrison on 'Soccer in the Streets'

'Celebrating the power of football' is this festival's slogan and speaking to the people behind some of the participating organisations underlines the truth behind these words. Englishman Pete Fleming founded the Lesotho-based Kick4Life charity with his brother Steve in 2005 and they use football to educate young people about HIV in a country with the world's third-highest prevalence rate (23.2 per cent) for the virus.

Kick4Life's work involves interactive learning about HIV prevention and arranging testing events and they have 300 volunteers working nationwide. So far they have reached 25,000 youngsters with the education programme and tested another 8,000. "For the testing events we use football as the hook," continues Fleming. "We arranged one-day football tournaments with interactive education focused on the importance of getting tested. We have trained up the national football team to deliver the curriculum to the youth. It is a tremendous tool to have."

The educational aspect, Fleming adds, "is also aimed at tackling the stigma surrounding the disease and developing skills in the young people to give them the personal qualities to live sensibly". It helps to have some high-profile supporters too – in 2008, England coach Fabio Capello gave Kick4Life some priceless publicity by attending a testing event.

Football's power to unite led to the foundation of another of the organisations involved at the Alexandra festival, Sport Against Racism Ireland (SARI). It was established to address growing problems of racism and intolerance in both the Republic of Ireland and Northern Ireland, and organises an annual two-day football festival in Dublin's Phoenix Park each September.

SARI's purpose, according to executive chairman Perry Ogden, is to "encourage integration through sport". Fittingly, their team at the Football for Hope Festival includes players born in South Africa and Romania, as well as youth leaders from Zimbabwe. Ogden adds: "Ireland is coming out of a mono-cultural society so it is a new thing to have a lot of people of different colour and background. We are really about bringing people together from different backgrounds and creating opportunities for people to mix."

The work of SARI's small team of volunteers includes an education programme and, from this year, a mini-tournament to mark World Refugee Day, organised in association with UNHCR, the UN’s Refugee Agency. "One team were Myanmar refugees based in County Mayo. That will become an annual event," Ogden says in concluding one of the countless encouraging stories to be heard here at 3 Square in Alexandra. Every single delegation, be they from Africa (13), Europe (six), the Americas (eight), Asia and Oceania (two each), or, last but certainly not least, the Middle East – whose Peace Team comprises Israelis and Palestinians – can deliver a similar message of hope. As DeAndre Harrison puts it, a ball really does have a lot of power.