This thesis examines the relationship between demographic ageing, as captured by temporal, within-country variation in the ratio of elderly to the working-age population – the dependency ratio – on citizens’ support for the welfare state. The research problem is vitally relevant considering the worsening demographic structure of advanced democracies, a process that is having considerable ramifications on the possibilities of financing comprehensive welfare states. Using a time-series cross-sectional design, and building on representative survey data from 13 advanced democracies, the thesis specifically assesses the relationship between the dependency ratio, and individual spending preferences towards 1) the welfare state as a whole, as captured by an additive index, 2) education policy, and 3) old-age benefits. It also assesses whether demographic ageing exacerbates attitude differences between age groups, thereby scrutinising some assumptions made previously on the issue of intergenerational cleavages. The thesis uncovers no significant relationship between the dependency ratio and general support for the welfare state. However, the dependency ratio is shown be positively correlated with citizens’ support for education policy, while being instead potentially negatively correlated with support for old-age benefits. The differences between these two policies, in terms of their enjoyed support, are important considering the presumed shift in welfare state priorities towards what is commonly called social investment. Indeed, they indicate that there may be popular support for the type of reform strategies whose purpose is to invest in tomorrow’s diminishing workforce, whereas the support for more compensatory old-age policies may instead be weakening. There are also signs that the positive effect on the support for education policy is lower among older individuals. This evidence is quite interesting considering the previous expectations of deepening intergenerational cleavages as a consequence of demographic ageing, but the weak indications of this development in previous empirical research.