This chapter extends classic social comparison research to explain how people think about group-based hierarchies and how they act within them. People spontaneously compare themselves to others in terms of relative status and power, not only as individuals but also as members of groups relative to other groups. Using a social dominance framework, the authors discuss the impact of such comparisons on socio-political attitudes and behavior. Social dominance theory describes how certain attitudes, values, and social practices enhance group hierarchies, whereas other attitudes, values, and social practices are hierarchy-attenuating. Power differentials within any type of group hierarchy are given by the balance between these forces that play out at three levels of analysis; in societal institutions (macro level), in intergroup relations (meso level), and among different individuals (micro level). The authors discuss not only how social comparisons shape hierarchy-enhancing and hierarchy-attenuating outcomes at each level but also how these outcomes, in turn, can mute the natural consequences of group-based power comparisons.