This paper analyzes the within-cohort relative wages of differently-educated workers in Taiwan. In a development context, the educational composition of a population often changes more rapidly than its age composition. Younger cohorts entering the labor force in Taiwan between 1979 and 1998 received far more education than older cohorts. As a result, the return to education within younger cohorts declined dramatically. Therefore, in a development context, it is important to take educational composition into account when analyzing the relative wages of different cohorts.