In two studies we assessed the role of distinctiveness threat, group-based emotions (angst, fear and anger), and prejudice on people's willingness to engage in collective action against immigrant groups. In Study 1 (N = 222) White British participants were either informed that in the next 40 years the proportion of immigrants in the UK is unlikely to change (control condition) or that there will be more immigrants than White British people living in Britain (threat condition). We obtained support for a sequential multiple mediator model in which threat predicted British people's willingness to engage in collective action via the emotions first and then prejudice. This finding was replicated in Study 2 with an Italian sample (N = 283). These results enhance understanding of when and why advantaged groups undertake collective action against disadvantaged groups by demonstrating that distinctiveness threats and emotions promote such actions.