Wars of national secession and ethnic cleansing have disfigured recent years. These conflicts stem from claims that the same territory is occupied by separate peoples for whom separate political arrangements should be made. Such claims are based on their supposedly distinct racial, ethnic, cultural or national identities. what, though, do such identities really amount to and what ought to be their role in determining the configuration and character of states? This has become a key concern of contemporary political philosophy and this book introduces readers to the materials required to address it: the concepts of race and ethnicity, cultural identity and nationality; the relevant political theories, including liberalism, communitarianism, and post-modernism; the topics of citizenship and migration, multiculturalism and the ethics of secession. This is the first comprehensive survey of a highly topical issue and its multidisciplinary approach should be of interest to relevance to courses in philosophy, politics, sociology and cultural studies, as well as of interest to general readers.