Existing political theory, particularly that which deals with justice and/or rights, has long assumed citizenship as a core concept. Noncitizenship, if it is considered at all, is generally defined merely as the negation or deprivation of citizenship. As such, it is difficult to examine successfully the status of noncitizens, obligations towards them, and the nature of their role in political systems. This paper addresses this critical gap by defining the theoretical problem that noncitizenship presents and demonstrating why it is an urgent concern. It surveys the contributions to the Special Issue of which the paper is an introduction, drawing on cross-cutting themes and debates to highlight the importance of theorising noncitizenship due to both the problematic gap that exists in the theoretical literature, and the real-world problems created as a result of noncitizenship are not currently successfully addressed. Finally, the paper discusses key future directions for the study of noncitizenship.
