In this paper I argue that when thinking about justice, political philosophers should pay more attention to social norms, not just the usual subjects of basic principles, rights, laws, and policies. I identify two widely-endorsed ideas about political philosophy that interfere with recognizing the importance of social norms—ideas I dub ‘compulsoriness’ and ‘institutionalism’—and argue for their rejection. I do this largely by focusing on questions about who can and should be an agent of justice. I argue that careful reflection on (...) these questions supports a kind of pluralism that reveals the importance of social norms, three types of which I discuss. (shrink)