The population transitions over the last century have produced important changes on age and cohort structures in most societies. Some of these effects have been extensively studied in many countries and from a cross-national perspective, as in the case of population ageing, although not always from a public policy perspective. The interrelations between the resultant age structural changes and public policy, considering the effects of changing structure on policy design, the impact of policy decisions on age structure, and the competing needs of different generations, require more research.

Rapid changes in age structure have often rendered inappropriate public policies designed to address population needs under different conditions. Moreover, the ability of policy makers to identify these changes and to adapt policies to meet emerging needs has not always been fast enough.