Given the ‘graying’ of especially the populations of most western nations, studies of factors contributing to well-being in later life are important and common. It is important to their accuracy that they be based on samples representative of the populations in the relevant age groups. There is general awareness that several characteristics such as sex, socioeconomic status, cognitive ability and personality are associated with study participation, but many researchers assume that this reflects life circumstances at time of recruitment rather than inherent individual characteristics that shape those circumstances throughout people’s lives. The Scottish Mental Survey 1947 6-Day Sample Follow-Up Study offered an unusual opportunity to test this assumption, as follow-up study participation data were available both in young adulthood and at age 77. Participation at age 77 was dramatically restricted relative to that in young adulthood. Cognitive abilities and a composite of conscientiousness-related variables independent of cognitive ability assessed in childhood predicted participation at young ages, but much more strongly at older ages. Evidence was available that these results were not specific to the recruiting and assessment methods used in this study. This suggests that participation in studies of aging is a function not just of contemporaneous circumstances but also of early-life cognitive and personality characteristics that have shaped those circumstances.