Richard Rose Central Academy in Carlisle has been plunged into special measures for the second time in four years.
Inspectors say standards at the school are unacceptable. Pupil achievement and quality of teaching were criticised.
The school was last put into special measures in early 2009, just months after it was opened.
Governers have written to parents to say they will respond to the issues quickly and effectively.
They have appointed a new executive principal to try and tackle the concerns.