Mathematical models based on evolutionary and ecological principles can help explain and predict variation in political organization and inequality across societies. This chapter introduces five major themes in human behavioral ecology that contribute to this goal. First, vertical power relationships between dominants and subordinates arise when resources are economically defensible and environmental or social circumscription limits outside options. Second, inequality increases when resources are durable and can be accumulated and inherited between generations within lineages. Third, egalitarian leveling can limit dominance behavior and inequality when there is a high degree of social interdependence, contributions to cooperation can be voluntarily given or withdrawn, or leveling coalitions facilitate collective bargaining. Fourth, organizational hierarchies are favored when they provide net benefits to group members compared to more egalitarian alternatives; inequality within these hierarchies is limited by the ability to replace aggrandizing leaders or move between groups. Finally, large-scale territorial hierarchies such as states and empires arise under conditions of escalating competition between groups over concentrated and defensible resources, such as high-quality agricultural land. The ecological parameters highlighted by these models define a multidimensional space of possibilities for human political organization and inequality.