The extant literature on oversight and investigations in Congress offers compelling explanatory frameworks for why members conduct oversight of the executive branch, but cannot account for why members choose to investigate one particular issue and institution over another. Via a new theory of investigative agenda-setting in the federal legislature, I argue that investigations in Congress constitute public narratives aimed at facilitating two collective goods: change of status-quo policy and accountability for institutional actors who have violated legitimate legal and policy frameworks. My project makes two primary contributions. First, I show that oversight is a fundamental part of the policymaking process: Both chambers, over time, have prioritized hearings devoted to issues, or policy problems, over hearings on waste, fraud and abuse in the executive branch. Second, I demonstrate that oversight, like the legislative process, is pluralistic. I propose a new typology of all investigative activity in Congress, and show that the five discrete types of oversight I identify respond to different member incentives over time.