Ingroup favoritism influences third-party norm enforcement: Third-party punishers are more lenient when an ingroup member has been unfair. By contrast, in 2-party contexts, where punishers are the victims of unfairness, group bias effects are absent or inconsistent. Thus, group bias appears to be particularly influential when enforcing fairness among others, but less so when protecting oneself from unfairness. This would have implications for theories of how cooperation and intergroup cognition interact, but a more direct empirical test is lacking. To this end, developmental data are particularly useful as they can tell us whether and if so how group bias and fairness norm enforcement are related from their first emergence. Using a minimal groups manipulation, we induced ingroup bias in 6- to 9-year-olds and tested their willingness to reject disadvantageous (more for you) and advantageous (more for me) resource allocations when paired with in- and outgroup members. Group bias did not affect children's rejections of unfair allocations, although they reported that it was worse when an outgroup member had more. Our findings suggest that ingroup bias does not influence children's costly endorsement of equality, indicating that children perceive the equality norm to be indiscriminate and enforceable across group boundaries.