Using two different measures of relative cohort size--one indicating the size and placement of an individual\u27s own birth cohort, and the other the ratio of young to prime-age adults in the United States in that year--it has been possible to isolate strong effects of the population age structure on wages in the United States over the past 33 years. These effects have been strong enough that virtually all of the observed change in the experience premium, and a substantial proportion of the changes in the college wage premium, can be explained by the relative cohort size variables alone. Even changes in the amount of within-group variance in wages appear to be largely a function of changing age structure, and absolute wage levels have been strongly affected by these demographic changes, suggesting that population growth can have positive effects on the economy