Proceedings of the United Nations Expert Group Meeting on Social and Economic Implications of Changing Population Age Structures Mexico City, 31 August - 2 September 2005. The Meeting considered the consequences of the worldwide demographic  transition and the changing age structure of populations, including the  different types of potential demographic dividends, intergenerational transfers, the effects of ageing on the macro-economy, the viability of social security systems, and health. The proceedings of the Meeting include a report of the  deliberations and edited versions of the contributed papers.