This article examines the potentially buffering effect of generalized social trust on fear in the aftermath of terrorist attacks and in situations of terrorist threat. It draws on comparative, longitudinal survey data, examining the cases of the 2011 Utøya terrorist attack in Norway, the 2016 Nice attack in France and the 2017 Barcelona attack in Spain; it also draws on a comparative news story experiment that examined the bolstering effect of social trust in relation to terrorist threat. The results show that high levels of generalized social trust before exposure to terrorism are linked to lower levels of fear after the event. This relationship holds for the longitudinal survey data and the news story experiment, and across national contexts. This result indicates a general bolstering effect of social trust. However, the size of effects vary between national contexts and incidents of terrorism. This indicates that the effect of trust is dependent on the social and cultural structures of trust in the different countries and on specific factors related to the attacks.