Do allies in collective action have a positive impact on political efficacy? Theoretical considerations and common sense might lead us to expect that advantaged group allies will be beneficial to the success of social movements. However, across five experimental studies, with samples from the United States and Germany (three pre‐registered, total N = 696, 48% women, Mage = 38), we find that such involvement does not significantly affect authorities’ reactions to the demands of disadvantaged groups. Decision makers were given information about proposals supported either by only disadvantaged group members or by disadvantaged group members and advantaged group allies. Their support, budget allocations, voting intentions and perceptions of movements and proposals did not differ as a function of this information. However, collective actions including allies did reduce perceptions of intergroup conflict. These results were replicated across different contexts with student and local politicians and with participants acting as parliamentarians in fictional scenarios.