Objectives: The present study sets out to investigate the relation of cognitive abilities to well-being and its interplay with key life course proxies of cognitive reserve and social capital in a large sample of older adults. Method: Three thousand eighty older adults served as sample for the present study. Physical well-being (EuroQoL-5D questionnaire) and psychological well-being (Satisfaction with Life Scale) as well as cognitive performance in terms of verbal abilities (Mill Hill vocabulary scale), processing speed (Trail Making Test part A), and cognitive flexibility (Trail Making Test part B) were assessed. Participants reported information on education, occupation, cognitively stimulating leisure activities, the different languages regularly spoken as well as family and close friends. Results: Moderation analyses showed that the relation of cognitive performance to physical and psychological well-being was significantly attenuated in individuals with a higher cognitive level of the first job after education, a larger number of midlife and current cognitively stimulating leisure activities, a larger number of languages regularly spoken, a larger number of significant family members and friends, and more frequent contact with and more confidence in significant family members. Conclusion: Present data suggest that the relation of low cognitive abilities to low well-being in old age is attenuated in individuals with greater cognitive reserve and greater social capital accumulated over the life course.