In 1980 New York State's Office of Mental Health began operation of a program designed to provide a secure treatment unit at each of the 23 state psychiatric centers. As part of a research project to assess the operation of the units, demographic and hospitalization data were gathered on all clients residing on, and admitted to, the 14 operational units over a five-month period in 1982. Clinical data and information on program operation were also obtained. Results indicated that the units were generally functioning as planned, primarily serving young male civil patients referred for assaultive behavior. The patients were significantly more likely to have been involved in incidents of dangerous behavior and to have been in restraint or seclusion than were patients on comparison wards. The study also found that the secure units had been effective in reducing the rate of such incidents for the patients served. However, some data suggested the presence of an imappropriate population on certain units.