PM's clampdown on gangs in riot aftermath
16 August 2011 Last updated at 09:12 BST
Gangs have been blamed for much of the rioting and looting that took place across England last week.
Now, the prime minister has declared that getting rid of them should be a national priority.
Many groups have been working with young people for years, helping to steer them away from violence.
BBC Breakfast's Jenny Hill reports from Leeds to see how they do it.