In two studies, we investigate the effect of individuals’ promotion and prevention focus on engagement in collective action. We show that responding to group-based disadvantage out of a sense of moral conviction motivates prevention-oriented– but not promotion-oriented– individuals to engage in collective action. Furthermore, holding such strong moral convictions about the fair treatment of their group causes the prevention-oriented to disregard societal rules against hostile forms of collective action (i.e., forms of action that are aimed at harming the interests of those held responsible for the group's disadvantage). Study 1 showed that prevention-oriented individuals, but not promotion-oriented individuals, with a strong moral conviction about the fair treatment of their group are willing to support both hostile and benevolent forms of collective action. Study 2 replicated this effect and showed that for prevention-oriented individuals but not for promotion-oriented individuals, holding a strong moral conviction about the fair treatment of the group overrides moral objections to hostile forms of collective action in the decision to support these forms of action.