This experimental study analyses the psychosocial effects of apologies directed to the victims of collective violence by the Basque Government and Parliament on Basque participants. It was expected that institutional apology would lead to an increase in collective guilt, shame and sorrow, while at the same time it would induce a more positive perception of emotional climate, as well as increasing positive beliefs and support for reparative actions towards the victims. As expected, when reminded of apology and past collective violence, participants reported higher shame and sorrow and agreed more with new reparations in comparison with the control condition, in which people were only reminded of past collective violence. Low identifiers exhibited a more positive perception of the social climate in the apology condition than in the control group, whereas high identifiers displayed the opposite pattern. In addition, high identifiers agreed more with defensive opinions related to past collective violence and reported lower agreement with reparations, although they did not express less collective guilt, or shame and sorrow.