Humans survive and thrive in groups. Groups provide the foundation for large-scale human cooperation, but they also lead to intergroup conflicts and structural inequalities. As young children navigate the social world, how do they come to understand groups and the broader structures they live in? I propose a framework in which individuals are nested within social groups, and groups are further nested within broader structures involving status hierarchies and underlying relations between groups. My talk will focus on several case studies situated within this framework. I start with a “minimal” case: What happens when children are randomly assigned to groups that they know very little about? I then move to cases in which children have more information about the groups, with a focus on the groups’ wealth status. I explore how children gradually develop more complex understandings of group hierarchies and social inequalities. The final case study examines how children explain differences between groups, focusing on gender differences. Together, these studies encompass both basic scientific research on the cognitive underpinnings of prejudice and applied work on interventions to combat biases and inequity.