The amount and organization of space on a psychiatric ward is one element determining the possibilities of the treatment program. Systematic observations by the Architectural Study Project of the movement of patients in 7 psychiatric wards of 5 general hospitals are reported. These observations lead the writer to the following opinions.More patients are kept on locked wards than need be locked up. Typically, there is need for more bed space on unlocked wards, less space on locked wards.Ward arrangement which provides several small day areas is to be preferred to one large dayroom.Ward dining rooms offer many advantages.Bare wards seem to imply that patients have little value and foster an institutional atmosphere. More comfortable furnishings foster a ward atmosphere of more respect for the patient.Since the use of hydrotherapy equipment is minimal at present, minimal facilities for hydrotherapy are adequate.There is need for planning suitable space for the administration of shock treatments.Special visitors' rooms do not seem necessary or desirable if suitable day areas are provided.Recreation areas are essential and are not always adequate.On the services studied, the one or two seclusion rooms provided are in general quite adequate.There is need in planning for careful consideration of the most reasonable alternatives to caring for critically ill patients, and for children on adult psychiatric wards. If the decision is made that such patients will be cared for on adult psychiatric wards, it should be recognized that additional staff and at times, additional space and equipment will be required.