This study examines the relationships between social capital and health and well-being among older adults who live alone to determine if older adults who live alone demonstrate different forms, adaptiveness, and consequences in their social needs and experience after retirement. Study also investigates in what way older adults who live alone coordinate their limited social assets and environment, and what negotiation strategies are evident in pursuing their emotional and social well-being. A cross-sectional comparative study was employed using data sampled from two companion longitudinal ageing studies: Health and Retirement Study (HRS) in USA and Survey of Health, Ageing, and Retirement in Europe (SHARE). A multiple questionnaire items were selected to examine how ageing alone—either voluntarily or not—is associated with declining social capital, mental and social health, and quality of life. Employing multivariate data analysis standardized estimates of path coefficients between the predictor variables were examined. Preliminary analyses indicate that there is variability in meaning and role of social capital—social network, social support, and social activity engagement—among those older adults who live alone across the societies. Results also indicate living alone does not necessarily lead to negative health outcomes; while the perceived quality of social capital was the most influential factor. Implications for policy making and health practice will be discussed to help better develop social infrastructure and institutional support aimed at older adults live alone.