New York State established the need for an assessment and treatment program targeting mentally ill inmates by surveying a 9.4 percent sample of the 36,144 inmates in the State prison system in May 1986. The survey concluded that 5 percent of the inmates were severely psychiatrically disabled, and another 10 percent were significantly psychiatrically disabled. When the functionally disabled inmates were added to those with psychiatric disabilities, there were 8 percent with severe disability and 16 percent with significant disability. These data established the need for a prison program to mitigate the disabling effects of psychiatric illness which prevent inmates from fully participating in the positive aspects of the correctional environment. The prison mental health services were also designed to relieve the suffering of prison maladjustment and help make the prison a safer place for both inmates and staff. Services provided by New York State include a fully accredited free-standing psychiatric center and mental health centers within 15 of the State's largest prisons. 1 figure, 13 references.