Influenced by social identity theory, psychologists have focused primarily on the role of shared identity in leading people to engage in collective action. In this study, we are concerned with the factors that lead individuals who do not share a collective identity to act in solidarity with an outgroup. We explored this question by looking at the narratives and motives that brought non-Palestinian university students to participate in collective action for Palestine. In-depth interviews with campus activists and a yearlong observation of campus debates over the Israeli-Palestinian conflict suggested a number of motives for solidarity activism. First, activists drew parallels between their in-group collective narrative and the collective narrative of the Palestinians. Second, an intersectional narrative of identity increased activist self-efficacy by highlighting the ways that activists were both marginalized and privileged. Third, activists explained their affinity to these narratives as rooted in personal experiences with marginalization and discrimination. A final motive arose through the practice of coalition building that further empowered students of different minority groups. Findings from this study contribute to an understanding of the current surge in Palestinian solidarity activism on college campuses in the United States.