In all democracies, whether presidential or parliamentary, the chain of political delegation is a complex process involving a multitude of principals, many of which are frequently replaced. This presents common-agency problems for bureaucrats and politicians—that is, they must be answerable to many different principals. The fractured and temporally unstable nature of democratic leadership makes political oversight of bureaucracy a particularly problematic link in the process by which the government is controlled by citizens. Legislatures can mitigate the agency problems associated with delegation using one of four approaches: contract design, screening/selection, monitoring/reporting requirements, and institutional checks. Thischapter examines the common-agency problem and the legislative control of the bureaucracy. It begins with a review of the positive and normative literature on delegation and oversight. More specifically, it considers the normative debate on who should control the bureaucracy, as well as the positive debate on who actually controls the bureaucracy. It concludes by addressing research frontiers in the study of oversight.