The present study examined the effects of antiprejudice norms on children’s ethnic attitudes by taking their antiprejudice motivations into account. In a sample of 767 native Dutch preadolescents we found evidence for both an internal and an external motivation to be nonprejudiced which were, respectively, positively versus negatively related to children’s out-group attitudes. Overall, children’s norm perceptions were linked to more positive ethnic attitudes, and this relation was partly explained by their internal antiprejudice motivation. Some normative aspects were found be less effective (moral rule to be nice and honest) than others (equality message) by stimulating an external motivation rather than undermining it and stimulating an internal one. Distinguishing between different normative sources further showed that parents and peers were more influential than teachers. Our findings underline the importance of including motivations in research on norms and out-group attitudes.