The town of Castro Marim in Portugal was a legal haven and later the site of internal exile for several thousand minor sinners and convicts from the Middle Ages until the first decades of the nineteenth century. Later, courts of the Inquisition and the state sent those convicted of minor offences to reside in the town, typically for periods of two to four years. Faced with the punishment of long-term obligatory residence, these newcomers had little choice but to engage in the economic activities around them: chiefly in salt extraction, fishing, boat building, agriculture, and smuggling. As a result, this use of exile to Castro Marim is more than a micro-history of a small town. It is a vivid example of social control as practiced by courts of the Church and state. It is also an example of the limitations of early modern royal authority.