Federal agencies perform many important tasks, from guarding against terrorist plots to mailing social security checks. A key question is whether Congress can effectively manage such a large and influential bureaucracy. We argue that Congress, in using oversight to ensure agency responsiveness to legislative preferences, risks harming agency morale, which could have negative long-run effects on performance and the implementation of public policy. More specifically, we argue that oversight’s effects on agency morale are conditional on whether oversight is adversarial or friendly. We assess our claims using a novel data set of the frequency and tone of hearings in which federal agencies are called to testify before Congress from 1999 to 2011 and merge it with data on agency autonomy and job satisfaction. Our findings suggest that agency morale is sensitive to congressional oversight attention, and thus speak to questions regarding democratic accountability, congressional policymaking and the implementation of public policy.