This Presidential Address develops a sociological concept of citizenship, particularly substantive citizenship, as fundamentally a matter of belonging, including recognition by other members of the community. In this conception, citizenship is not simply a fixed legal status, but a fluid status that is produced through everyday practices and struggles. Historical examples illustrate the way in which boundaries of membership are enforced and challenged in everyday interactions. The experience of undocumented immigrant college students is particularly illuminating. These students occupy a position of liminal legality, which transcends fixed categories such as legal and illegal. As they go about their daily lives, their standing is affirmed in some settings and denied in others. Furthermore, the undocumented student movement, which asserts that education is a human and social right, represents a form of insurgent citizenship, one that challenges dominant formulations and offers an alternative and more inclusive conception.