A growing literature shows that popular attitudes towards public policy reforms are sensitive to issue knowledge. It is also widely believed that well-informed people tend to prefer different policy reforms than ill-informed people. We apply these general insights of public opinion research to the analysis of attitudes towards welfare reform in the wake of demographic ageing. Our study draws on new experimental evidence regarding three advanced democracies with ageing populations – Germany, Spain and United States. Based on newly conducted online surveys of the general population and an experimental approach, we examine how ‘hard knowledge’ is related to the support for concrete public policy reforms. Specifically, the paper analyzes how information on the financial sustainability of pension systems affects support for various avenues of welfare state reform. The first objective of the project is to ascertain how the random exposure to the treatment – which varies in content across the study countries – shapes attitudes toward social spending, and, in that case, what kinds of outcomes are most strongly affected. By exploiting variation in respondents’ prior pension knowledge, our second objective is to find out to what extent measured impacts are driven by priming or information effects, respectively. Finally, we also set out to discover what individual characteristics (age, gender, education) moderate the information effect on policy preferences. The project has important implications for the dynamics of public discourse on welfare reform.