The government's overhaul of the mental health system must give more protection to children, a charity has warned.
Ministers' plans have proved to be controversial
The Young Minds group says 1,000 youngsters are admitted to adult wards each year - almost one third being detained against their will.
Many are abused or left traumatised by the experience, the charity says.
Young Minds is urging MPs, who will debate the government's Mental Health Bill next week, to ensure new laws consider children's welfare.
The charity says youngsters are often subjected to verbal, physical or even sexual assault while in hospital.
Many will spend a month or more on a ward, and most will have no arrangements made for their education.
And the charity sayd that the number of children's mental health beds is unequal across the country - with London having three times the proportion of beds per person than Yorkshire.
The Mental Health Bill has proved controversial, and has been making slow progress through Parliament.
The House of Lords rejected its provisions that would allow the enforced detention of people who are mentally ill, even if they have not committed any crime.