When analysing the legitimacy of the welfare state, perceptions of the overuse and underuse of welfare are of great importance. Previous literature suggests that many people perceive overuse (misuse or fraud), and there is evidence that people also perceive underuse (non-take-up) of welfare benefits. Perceptions of overuse have therefore been called ‘the Achilles’ heel of welfare state legitimacy'. We analyse data from the European Social Survey for 25 countries and investigate the occurrence and the individual and contextual determinants of overuse and underuse perceptions. We find that both overuse and underuse perceptions are prevalent in all European countries. However, whereas overuse perceptions are more related to ideology, collective images of welfare recipients and selective welfare regimes, underuse perceptions are more shaped by self-interest and the levels of unemployment and social spending in a country. Instead of one Achilles' heel, welfare state legitimacy seems to have two weak spots.Key words: Benefit abuse, European Social Survey, non-take-up, welfare attitudes, welfare states