This paper describes an integration of the stereotype content model with social identity theory in which we theorise links between the legitimacy and stability of status relations between groups on the one hand, and stereotypes of warmth and competence on the other. Warmth stereotypes associate with the perceived morality of inequalities, so we reason that high and low status groups are more differentiated in warmth in illegitimate status systems. Also, stereotypes of competence explain status differences, so differences in stereotypical competence may be more pronounced when status is stable rather than unstable. Across two experiments high and low status groups were more sharply differentiated in warmth in illegitimate than legitimate status systems, as predicted. The effect of stability on competence was less clear, as groups were clearly differentiated in competence in all status systems. Implications for the roles of warmth and competence stereotypes in social change are discussed.