Scholars have ignored the most important question in one of the most famous constitutional law cases, obscuring the machinations that spawned the dispute. This Article sheds light on the events that precipitated Marbury v. Madison and also explains when an appointment vests. Thomas Jefferson famously refused to deliver a commission to William J. Marbury, causing the latter to seek a writ of mandamus from the Supreme Court. The received wisdom supposes that Jefferson’s refusal rested on the grounds that Marbury had not been appointed a justice of the peace precisely because he never had received a commission. In fact, Jefferson’s delivery argument was a post-hoc rationalization, having nothing to do with his actions in March of 1801. John Adams’s midnight appointments incensed Jefferson, leading the new President to treat all of the justice of the peace appointments as nullities. To Jefferson, the failure to deliver commissions to some of those appointees mattered not a whit. What seems to have been far more significant is his sense that the justices of the peace served at his pleasure. Acting on this belief, he simultaneously removed them all and recess appointed most of them, save for more than a dozen, including William J. Marbury. This Article also addresses whether William J. Marbury and the other midnight appointees who never received their commissions were nonetheless appointed, considering five theories of when an appointment vests: when the Senate consents; after consent but before commissioning; when commissioning occurs; with the delivery of a commission; and with acceptance of the office. In the course of considering these theories, the Article discloses the surprising fact that Thomas Jefferson, as Secretary of State, endorsed the second theory, namely that appointments vest before the act of commissioning. Moreover, well before Marbury v. Madison, the Adams Administration likewise concluded that appointments could vest prior to any commission being issued or delivered. Despite this convergence, the Article contends that none of the five theories is correct because each reads the Constitution as enshrining a single answer regarding when an appointment vests. There is no single answer. Rather an appointment vests whenever the President determines that it shall. The Constitution grants power to the President to appoint, never precisely specifying when or how an appointment vests. By not specifying when or how appointment is made, the Constitution leaves it to the President to decide the manner in which he appoints. This conclusion derives from a general principle of constitutional law: When the Constitution grants power to an entity but does not specify the precise means by which it will be exercised, the grantee may decide the means of exercising it.