They hope that if bullies know they are members of a gang then they won't go after them.
Around 5,000 children aged 11-16 were asked loads of questions about school in a survey, and half of them said they had been a victim of a crime.
Even more than that - some 60% - said they were worried about violence at school or during their journey there and on the way home.
The survey was done for the Youth Justice Board for England and Wales, a group that thinks up ideas to help stop kids breaking the law.
Talking about kids who join gangs, the head of the Board, Lord Warner, said:
"It's a case of if you can't beat them, join them."
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