Abstract: This chapter examines the U.S. constitutional law of citizenship, particularly as a status recognized by the Constitution entailing rights and duties. It first traces the evolution of the institution of citizenship in the Constitution and how federalism has contributed to the maintenance of multiple citizenship statuses rather than a uniform common citizenship. It discusses the constitutionally salient rights of citizenship, and citizenship itself as a right, before turning to civic duties implied by the Constitution. Against that background, it focuses on women’s citizenship, and the slow dismantling of gender differentiation in civic rights and duties. It also explores the extraterritoriality of citizens’ constitutional rights and concludes by examining the weak constraints that constitutional rights place on naturalization and immigration policies.