Japan is expected to be one of the most aged society in the world in 2000. It is estimated that about a quarter of the whole population in Japan will be 65 and over in 2025. To solve problems related to the trend, the Ministry of Construction started a five-year research and development project on design for the aged society in 1987. The author took the leading role in defining the aim of the project, and put Design for all ages as the key concept, discarding the traditional idea of special design for the aged. It is a clear departure from age segregation that has been the idea of sheltered housing scheme. It assumes that residents will age in place, and that the dwellings should be able to respond to the changing needs of residents.