Oversight hearings should be an important congressional tool for controlling recalcitrant agencies, but it is not clear that this should always be equally true. The logic of principal-agent models of legislative policy control implies that oversight might sometimes, but not always, be superfluous to said control. Here, I reintroduce oversight hearings to theories of policy control and argue that congressional committees conduct oversight hearings primarily as a response to the extent to which agencies have different policy preferences from them and as a function of their capacity to conduct hearings cheaply. I test these hypotheses using committee hearings data (Policy Agendas Project) from both the U.S. House of Representatives and the Senate from 1947 to 2006 and provide support for theoretical arguments about the institutional nature of legislative policymaking strategies and ultimately help clarify the role of oversight in legislative-executive relations.