This chapter considers what is arguably the best-known recent defence of an ontological argument: Alvin Plantinga’s ‘victorious’ modal ontological argument. I begin by reviewing Plantinga’s assessment of previous ontological arguments. These arguments then provide inspiration for Plantinga’s argument, which avoids certain pitfalls of the previous ones. However, as I explain, there is still the problem of reverse arguments: the problem is that there is no better reason for a neutral agnostic to accept the premises of Plantinga’s argument than to accept the premises in a parallel argument for atheism. I consider whether one could still defend Plantinga’s argument by providing a sub-argument to support Plantinga’s crucial premise that a maximally great being is possible. I try out an argument based on ‘modal continuity’ with respect to degrees of value. I make use of recent work in modal epistemology to supply a defeasible, value-uniformity principle, whereby all degrees of value alike are possible. This principle, if true, supplies some reason to think that maximal value – which arguably entails maximal greatness – is possible. I consider various objections, including parody arguments, as a way to test his argument. Finally, I provide some empirical conditions for determining whether Plantinga’s newly reinforced argument may, or may not, count as ‘successful’.