This article is an inquiry into cosmopolitanism, nationality and citizenship and how they might be presented in the classroom. I argue that cosmopolitanism does not contradict nationality and citizenship, and that cosmopolitanism should be a restraint on nationalism. Common sense morality accepts that personal relations are a source of moral obligations separate from moral worth of humanity in general. Nationality should be grouped with universal relations like freedom and equality and justified in universal terms. Thinking about nationalism is important for teachers, because there is a tradition for using schools to encourage nationalism.