People are sensitive to norms, but under what conditions promoting anti‐prejudice norms reduce prejudice remains unclear. Three studies among Dutch participants (total N = 700) examined the effects of (in)equality norms on prejudice towards migrants. To gain greater clarity, we also examined how potential boundary conditions—namely economic and social ideologies—moderate this relationship. A norm of equality was measured (Study 1) or manipulated (Studies 2a and 2b). In Study 1, a perceived norm of equality predicted lower prejudice towards migrants, operationalised as cold feelings, social distance, and perceived outgroup threat, through the increased personal endorsement of equality, particularly among (economic) rightists. In two experiments (Studies 2a and 2b), as well as in a joint analysis of both studies, we found that inducing an equality norm (vs. not) mitigated prejudice towards migrants, but only among (social) rightists. These findings highlight the positive role of social norms promoting equality in combating prejudice and the importance of considering boundary conditions for this role, such as ideology. We discuss the implications for theory and practice regarding prejudice (reduction). Please refer to the Supplementary Material section to find this article's .