Metoikia, the legal system for metic registration, taxation, and enforcement evolved over the course of the 5th century. What sort of thinking led to the construction of the ‘metic’? How did the idea of the metic develop and why does its development matter? In order to answer these questions, I propose we understand the metic in Athens as an explicitly racialized type of foreignness, rather than as a neutral legal category, ‘quasi-ethnic identity’, or ‘ideological foil’ for the citizen. Few scholars have attempted to understand the nature of metoikia itself or the realities of metic life that their racialization implied, preferring instead, to view it as one type of ‘Other’ against which the citizen was constructed or contemplated. Our quest here is to engage the legal, social, and political category of the metic in the 5th and 4th centuries BCE. I argue that it functions as a type of ‘race’ in antiquity and that the idea of a biologically coherent and ‘natural’ Athenian citizen emerges as a result of the creation of metoikia.