This Article examines the departmental structure of the executive branch, which facilitates, channels, and delimits the exercise of executive power. This structure is grounded in the text of the Constitution, which refers to “Department[s]” in the Necessary and Proper Clause, Appointments Clause, and Opinion Clause. The concept of the department also played a key role in the Framers’ constitutional theory of checks and balances. Public law has implemented the scheme that constitutional text and theory outlined. Legislation, case law, and executive branch practice have constructed departments within the executive branch as durable repositories of authority that distribute and rationalize power. Departmental protections against official arbitrariness have been tested in recent events, such as the Special Counsel Investigation, the effort to add a citizenship question to the census, and controversies concerning the leadership of the Consumer Financial Protection Bureau. The departmental structure of executive power must be maintained with renewed investments from each of the constitutional branches.