A sample of 309 police officers in Cincinnati and Hamilton County, Ohio, were interviewed about their contacts with mentally ill individuals and about their need for various kinds of information and assistance from the mental health system. During a one-month period, almost 60 percent of the officers had responded to at least one call involving a presumably mentally ill person, and 42 percent had responded to more than one such call. Twenty-two percent had dealt with a presumably mentally ill person who was also mentally retarded. Police officers indicated that they most needed access to information about an individual's past history of violence or suicide attempts, and quick on-site assistance by mental health professionals in assessing suicidal or hostile mentally ill persons.