Citizenship, denoting full and active membership of the national and political community, has been recognized as a critical concept since ancient times. However, three key and related changes have occurred to each of the basic components of this concept that have altered dramatically to whom and to what it now refers, and the contexts in which it seems proper to use it. First, the scope of membership or who can be a citizen has broadened considerably. Second, the rights and duties of citizenship have likewise been transformed. Finally, the contours of the political community, or the loci...