Predicting the labour market effects of population ageing is a complex exercise. An older—and, in some cases, smaller—population immediately suggests a contraction of labour supply. But the implications for employment are not obvious. Labour supply also depends on labour force participation rates. Besides, demand for labour is bound to be influenced by the wage effects of supply-side shifts, not to mention attendant changes in productivity and capital accumulation, and the increased pension and health-care costs that a higher dependency ratio would entail. Spiezia examines these interrelated issues and the measures taken by OECD countries to cope with ageing.