Are young people less likely to punish undemocratic behaviour? I employ experimental data from 5 studies, 10 countries, and 17 unique country-year samples to re-assess the proposition that young people are less committed to democracy than older people. The studies consist of 4 conjoint experiments and 1 vignette experiment, which all permit estimating an interaction between undemocratic candidate behaviour and respondent age on voting intentions. I find that the interaction between undemocratic behaviour and age is negative—such that punishment of un-democratic behaviour increases with age—in all studies and in almost all country samples. Moreover, the interaction is approximately linear and strongly significant statistically in the pooled sample and in the majority of studies. Thus, young people are less likely to sanction undemocratic behaviour than older people. This letter contributes with the hitherto most comprehensive empirical contribution on age differences in commitment to democracy judging from the punishment of undemocratic behaviour.