Breakfast's Graham Satchell visited one of the charity's projects in Middlesbrough, where it's worked with more than two thousand young people at risk of prostitution or sexual abuse over the past three years:
Just after 9pm and a group of workers from Barnado's load up for the night.
For the last three years in Middlesbrough, the children's charity has been helping girls - some as young as 12 - to get out of prostitution.
It starts by offering sandwiches and condoms.
Most of the girls tell a similar story. Many end up in care after being abused at home. They start working on the street to feed a drugs habit.
Louise tells me:
"I don't like doing this - I don't enjoy doing it at all. But it's just a way of making money and providing for my drugs."
Back at base, the project leader Wendy Shepherd briefs her team for the next run on the bus.
In recent months they've become increasingly worried about a new problem: the number of young boys being abused and sold for sex.
Wendy tells me:
"I think the abuse of young men and boys is much more organised. You're really talking about networks of older men who are purchasing sex from young boys and then passing them on to their friends and mates."
Its impossible to gauge the scale of the problem - but Barnados have seen 185 young people in Middlesbrough in the last three years and they've helped 36 out of prostitution.
One of the success stories is Trudy, who says she drifted into prostitution at 13 or 14.
Trudy knows how important it was to get off the streets. Three of her prostitute friends have been murdered in the last three years.
She tells me:
"There's more and more children under the age of sixteen that are being found murdered - its not going to stop, especially while young girls are putting themselves at risk."
The government has changed its guidelines on child prostitution - they're now seen not as criminals but as victims.
Nonetheless the oldest profession in the world is attracting some of the youngest in society - both girls and boys.
