This chapter considers the many tasks of finance ministries, trying to separate their structural role from related and expedient functions. The finance ministry’s role is to consider a government’s taxing and spending in total and serve as a counterbalance to the demands of line ministries. Its work on the budget, aggregate fiscal policy, and many more specialized tasks is ultimately in service of that core function. The chapter discusses how finance ministries are embedded in a system of fiscal governance, how their functions can be structured and staffed, and how they came to take their present form. There is no one good model finance ministry, but many cases to learn how others have responded to new problems, if only to avoid their mistakes.