The age structure of a region’s population affects many areas of social and economic development across all sectors, including employment, housing, welfare, health and education. This is mainly because different age groups tend to have different needs both at a family level and a social policy level. Also related to this are the differing ethnic structures between the regions, which can explain some regional differences in social and economic factors. Birthplaces are also related to ethnicity. This paper investigates age, birthplace and ethnicity for the period 1986 to 2001 by the regional council areas of New Zealand. It also looks at the projected age structures into the future between 2001 and 2021 and the wave effects these may generate.