This chapter explores two theories central to understanding the behavior of federal prosecutors. First, principal-agent theory is introduced to frame the relationship between national political actors, or principals, in the executive and legislative branches and their agents—U.S. Attorneys (USAs). In that exploration, the chapter focuses on problems of adverse selection and the monitoring of agents by principals. Second, the chapter considers career ambition theory as it pertains to the post-service employment opportunities of USAs. That discussion focuses on the potential of USAs to ascend to higher positions in the administration or secure nomination to the federal bench, both of which require the approval of principals in the executive branch.