Kant’s Critique of Pure Reason contains four distinct objections to the Ontological Argument (OA), only one of which contends that existence is not a predicate (E ~ P). After some preliminary discussion of Kant’s treatment of the ens realissimum, this chapter will turn to his four objections to the OA. As will be seen, of Kant’s four objections to the OA, two are based upon an analytic reading of the statement ‘God exists’ while the other two follow a synthetic reading of the statement. Moreover, the first two grant for the sake of argument that existence is a predicate. This will lead us to two related issues: whether Kant’s division between real and logical predicates adequately captures all subject–predicate relations; and whether or not Kant has taken proper account of the difference between the ‘marks’ (Merkmalen) of concepts versus the properties of objects. After some discussion of these issues and their bearing on his famous hundred-dollar example, we will turn to three recent strategies used to defend Kant’s case for (E ~ P). It will be argued that none of these strategies succeeds, and that, in the end, there may be no definite argument for establishing whether or not existence is a predicate.