We are women, we are men. We are refugees, single mothers, people with disabilities, and queers. We belong to social categories that frame their action, self-understanding, and life options. But what are social categories? How are they created and sustained? How does one come to belong to them? To answer these questions is to offer a metaphysics of social categories, and that is the project of Categories We Live By. The key component in the story offered is a theory of what it is for a feature of an individual to be socially meaningful in a context. People have a myriad of features, but only some of them make a difference socially in the contexts people travel. The author gives an account of what it is for a feature of an individual to matter socially in a given context. This the author does by introducing a conferralist framework to carve out a theory of social meaning, and then uses the framework to offer a theory of social construction, and of the construction of sex, gender, race, disability, and other social categories. Accompanying is also a theory of social identity that brings out the role of individual agency in the formation and maintenance of social categories.