Key messages: Population ageing is both a challenge and an opportunity for all OECD countries. There are significant cross-country differences in the rate of population ageing and some countries face much bigger challenges than others. Therefore, the scale of the measures required is not the same across countries nor is the urgency with which reforms need to be put in place. Nevertheless, all countries will need to mobilise more fully the potential labour resources of older people as the key policy response to population ageing.