Situations of vulnerability are a set of circumstances in which individuals experience difficulties that may interact to increase the risk of having coping challenges with a negative impact on their life, and are associated with reduced life satisfaction. Social support may moderate the influence of situations of vulnerability. This study aimed to document situations of vulnerability and examine their association with life satisfaction and social support, and its moderating effect on the association between situations of vulnerability and life satisfaction among older women and men. Methods. Secondary analyses of cross-sectional data on 21,491 respondents aged ≥65 from the Canadian Longitudinal Study on Aging were conducted separately for women and men. Confirmatory factor analysis identified a latent vulnerability variable from physiological, psychological, socioeconomic and social indicators. Regression models were used to estimate the association between vulnerability and life satisfaction, and the moderating effect of social support. Results. Respondents were aged 65 to 89 (73.4±0.04). For both women and men, reporting more depressive symptoms, chronic conditions and insufficient income best explained vulnerability, followed by dependence in basic activities of daily living, less social participation and living with fewer people. Vulnerability was associated with lower life satisfaction (p<0.001) for both sexes, and social support acted as a buffer against vulnerability (p<0.001) for women. Conclusions. Results confirm the multidimensionality of vulnerability. The buffering effect of social support in women reinforces recommendations concerning policies and interventions designed to increase networks, but further research is warranted for men.