The study investigates the extent to which the perceived physical environmental quality of housing facilities for people with severe mental illness accounts for perceived social environmental quality. Twenty facilities were assessed by people with psychiatric disabilities (residents), staff, and experts with regard to the physical environmental aspects of visual pleasantness, indirect environmental effects, overall physical quality, and the social environmental indicator of social relationship. The results suggest that residents’ and staff's physical environmental quality perception accounts for social relationship quality perception, whereas experts’ environmental assessment does not. Moreover, the staff reported a more positive social relationship perception than the residents.