The number of people with dementia in Japan is increasing due to change of aging population structure. As a model for alternative care form for people with dementia, group living is regarded as worthwhile to be considered. The aim of the paper is to clarify the basic characteristics of life and utilization of residential space in group livings. Four units in three group homes in Japan were selected as survey fields. Observation surveys were carried out in 1995 and 1996 and behavior maps were drawn every 10 minutes. This survey was placed as the first survey for group livings and played an important role for making standard in architecture and care. Major results are shown as follows: 1. Daily activities and the usage of spaces are largely influenced by the care program and the operational policy of each group living. Therefore, the method of care and operation should be considered carefully with the physical environment. 2. Common spaces such as living room, kitchen and day room plays an important role for their daily activities, because that most of the residents stay there for considerable period during daytime. How design these spaces directly affect the quality of life of the residents. 3. Layout of each private room and common space seems very crucial point in designing these kind of facilities, in order to enable people with dementia to live their lives more independently and voluntarily. 4. Careful organization of a group mixed with different levels of dementia results in therapeutical good effects on severe damaged group in verbal communication or other activities. 5. This paper mainly focused on the activities and lives in common spaces. It will be the future theme of this study to consider the environment for the people with dementia more wider area, outside of the facilities and regional level.