Studies on historical episodes of intergroup violence and conflicts have underlined the complicit role of bystanders in extreme intergroup dynamics. In regard to contemporary multicultural societies, the concept of intergroup indifference has recently been introduced, defined as being uncaring vis-à-vis arbitrary policies affecting other social groups. In the present manuscript, the reasons why an indifferent position towards minorities may imply some prejudicial attitudes towards them will be analyzed. In particular, moral disengagement and lack of social responsibility are considered to be variables that could explain why indifference might mask prejudicial attitudes and a lack of altruism for out-groups. The results show that moral disengagement and social responsibility are indeed significant mediators of the prediction of intergroup indifference to racism and altruism. In particular, the mediation model shows that moral disengagement partially mediates the path from indifference to racism, while social responsibility partially mediates that from indifference to altruism.