The Mental Health Commission says an unacceptable number of care centres are failing to meet statutory requirements.
The Commission says 40% of facilities are not compliant with individual care plan regulations and 56% are not meeting minimum staff requirements.
Its annual report for 2013 also says the extent to which physical restraint and seclusion are still used is unacceptable and too many children are still being assigned to adult centres.
Chief Executive Patricia Gilheaney says the sector is still lagging behind.
Ms Gilheaney said: "There appears to be a period of stagnation - we would hope that that is to be a blip and that we will return to incremental improvement.
"But we're getting impatient with incremental improvement - we really, really need to push on now at this stage and ensure 100 compliance in service provision."