The Doomsday Argument and the Simulation Argument share certain structural features, and hence are often discussed together (Bostrom 2003, Are you living in a computer simulation, Philosophical Quarterly, 53:243–255; Aranyosi 2004, The Doomsday Simulation Argument. Or why isn’t the end nigh, and you’re not living in a simulation, http://philsci-archive.pitt.edu/190/; Richmond 2008, Doomsday, Bishop Ussher and simulated worlds, Ratio, 21:201–217; Bostrom and Kulczycki 2011 A patch for the Simulation Argument, Analysis, 71:54–61). Both are cases where reflecting on one’s location among a set of possibilities yields a counter-intuitive conclusion—in the first case that the end of humankind is closer than you initially thought, and in the second case that it is more likely than you initially thought that you are living in a computer simulation. Indeed, the two arguments do have some structural similarities. But there are also significant disanalogies between the two arguments, and I argue that these disanalogies mean that the Simulation Argument succeeds and the Doomsday Argument fails.