We examine cross-national variation in (a) loneliness trajectories and (b) the association between common social risk factors and chronic loneliness in middle and older adulthood. Using longitudinal data, we assess the country-level prevalence of loneliness trajectories (chronic, transitory, and no loneliness) and the extent of common social risk factors for loneliness (living alone, widowhood, divorce, no grandchildren, having chronic conditions, and never working) among adults 50 and older in 20 countries covering 47% of the global population in this age bracket. Additionally, we compare how the associations between social risk factors and chronic loneliness vary across countries. We find considerable variation in the prevalence of chronic loneliness cross-nationally, ranging between 4% (Denmark) and 15% (Greece) of adults 50 and older. Living arrangements have the most consistent association with the likelihood of chronic loneliness across countries, with those ever living alone having an 8% higher likelihood of chronic loneliness on average across countries, with a range of 2%-25%. Additionally, those who never report working and those with chronic conditions have a higher likelihood of chronic loneliness across more than a third of the countries. These results suggest that policies and interventions targeted to middle age and older adults living alone and with limited work histories or with chronic conditions are critical in reducing the public health challenges of chronic loneliness.