What is European Union citizenship and why it is prized? Is the good that European Union citizenship seeks to promote simply an economic one, namely, market integration? Or is its value linked with other, bigger objectives, such as political integration and the creation of an ever closer union among the peoples of Europe, be they the citizens of its member states or all residents in the territory of the union? And if, on the other hand, EU citizenship and intra-EU mobility are viewed as instantiations of market integration, where do the individual, his/her experiences, and his/her social world feature in all this? In addressing these questions in this chapter, I opt for an integrated approach that blends insights from history, politics, law, and sociology.