ABSTRACT
This chapter addresses the challenges posed by the concepts of generation and cohort. After a brief discussion of the common uses of the concept of “generation,” this chapter turns to several landmark essays that remain critical for contemporary thought on cohort. It then examines issues related to measuring and analyzing cohort, including challenges associated with demonstrating cohort effects, handling the age-period-cohort problem, linking lives and history, examining cohort trajec tories, and understanding the societal significance of cohort. As the chapter nears its end, it entertains a few metaphors of cohort aging that exist in popular culture and social science theory. It closes with a discussion of the problem of “historical specificity.” That is, because most developmental research is cross-sectional, and because even the most long-standing of longitudinal studies are typically composed of members of a single birth cohort, little is known about the extent to which developmental knowledge is historically specific. Yet our theory and data are dis cussed as if they are valid across historical periods. The problem of historical specificity has been largely disregarded, but is serious and runs throughout develop mental research. It is a problem to which we must now respond.
