Illinois is promising to improve safety at its youth prisons and offer inmates better educational and mental health services.

The Department of Juvenile Justice agreed to the improvements after the American Civil Liberties Union of Illinois threatened to sue.

The two sides plan to ask a federal judge Wednesday to approve their plan, which calls for investigators to study youth prisons for six months and then recommend changes.

The Department of Juvenile Justice houses about 1,000 children and teenagers.

Watchdog groups say many don't get a decent education or proper treatment for mental illnesses. They also report frequent fights, children being put in solitary confinement for weeks and inmates staying behind bars after they're supposed to be released because the state has nowhere to send them.