PURPOSE: to investigate if the increased risk of disability onset among older people who live alone could possibly be moderated by either high social participation or by being satisfied with the social relations. DESIGN AND METHODS: logistic regression models were tested using two waves in a study population of 2,697 non-disabled older men and women from The Danish Longitudinal Study on Preventive Home Visits. RESULTS: living alone and low social participation were significant risk factors for later male disability onset. Not being satisfied with the social relations was significantly associated with onset of disability for both genders. Among men who lived alone low social participation was a significant predictor of disability onset [odds ratio, OR = 2.30 (1.00-5.29)]; for cohabiting men social participation was not associated with disability onset, [adjusted OR = 0.91 (0.49-1.71)]. Similar results were present concerning satisfaction with the social relations among men. There was no significant interaction for women. CONCLUSIONS: the study suggests that men who live alone can possibly alleviate their risk of disability onset by being socially active and by having access to satisfactory social relations. Women do not seem to benefit as much from cohabitation as men, although women who live alone and who are not satisfied with their social relations also constitute a significant risk category.