Objectives: To clarify the factors associated with risk for assisted living among community-dwelling older people, we conducted a large-scale survey in an urban city in Japan. Design: Population-based cross-sectional study. Setting: A mid-sized urban city in western Japan with a population of approximately 410,000. Participants: Nondisabled and nondemented community-dwelling older people (>= 65 years). Measurements: A self-administered postal questionnaire, including a health checklist for the screening of older people at high risk for assisted living, as well as demographic/sociodemographic questions on sex, age, present illness, living alone, duration of residence within the current city, community participation, and employment status, was distributed. Results: There were 41,796 returned questionnaires (response rate: 73.8%, average age: 72.0). Participants who were at high risk for assisted living accounted for 25.2%. The independent factors associated with risk for men and women were higher age, present illness, lack of community participation, unemployment, and <20 years of residence. Living alone was a significant factor for men, whereas it was insignificant among women. The types of illnesses among people at risk were different between men and women. Conclusion: Higher age, present illness, and several social factors were independently associated with high-risk status for assisted living in the large-scale whole community survey, and there was a sex difference. Our results may provide basic information for the further application of effective preventive intervention in the community. (C) 2016 Elsevier Ireland Ltd. All rights reserved.