Governments around the world traditionally distinguish insiders (citizens) from outsiders (foreigners). Yet citizens of European Union now have at least two citizenships that of their member state and that of Europe. Over the past half century an extensive set of supranational rights has been created in Europe that removes member governments' authority to privilege their own citizens, a hallmark of sovereignty. European citizenship not only provides individuals with choices about where to live and work but also forces governments to respect those choices. Explaining this innovation why states cede their sovereignty and eradicate or redefine the boundaries of the political community by including foreigners, this book analyzes the development of European citizenship and the evolution of supranational rights.