This chapter describes the connections between citizens' sense of political identity, the immigration and citizenship policies pursued by that society's government, and theories of the role and structure of the just state. It helps readers to develop philosophical ways of thinking about the issues of nationalism, multiculturalism, immigration and citizenship policy, and secession so as to encourage reasoned ways of solving conflicts occasioned by these issues. Citizenship and immigration policies articulate a society's conception of what is involved in being a member of that society. However, immigration policy involves not only issues of distributive justice but also issues relating to the social and political identity of a state. The linkage between multiculturalism and consent-based conceptions of political association has not, been sufficiently appreciated by communitarian supporters of multiculturalism. Political theory cannot change the fact that important and morally legitimate political causes usually produce casualties.