This article builds a framework for a relational approach to segregation that emphasizes structures of interactions, transactions, and ties between and within social categories. Rather than explaining segregation with dominants imposing formal rules or homophilic people sorting themselves, I highlight segregation's emergence amid dueling control efforts among actors with malleable categorical identities. And rather than assuming segregation necessarily fuels cycles of inequality or persecution, I identify nuanced advantages and disadvantages for different actors in social conflict. I also explore an underappreciated role of institutions in segregation: They guide relations across different domains of activity that may have different degrees of segregation. An overarching theme is that segregation is not a specific thing with regular causes and effects but an inherently contradictory structural feature of relations that evolves as actors struggle for control.