Since the treatment of juveniles as in-patients in a special unit is somewhat unusual in mental hospital practice, a brief introduction may not be out of place. These units might be considered as another development in a trend which has been progressing for the past 25 years. Until 1930 certification of all admissions to mental hospitals and a mainly custodial régime ensured the majority of patients being largely the end-results of psychiatric illness. Since 1930 the steadily increasing use of the voluntary system has brought many patients to hospital at a stage when their illness can be favourably influenced by modern therapeutic methods. An associated development was the increased provision of wards or units separate from the chronically disturbed cases, or even, as at this hospital, a complete villa system of detached and semi-detached wards for mainly voluntary adult patients.