It is convenient, though not obligatory, to hypostasize content and speak of the propositions expressed by the sentences of the theory. That allows us to neatly separate the problem of determining the ontological commitments of a theory (set of sentences) into two components: What propositions are expressed by the sentences of the theory? And, what are the ontological commitments, that is, the existential entailments, of those propositions? Indeed, we could then choose to construe theories as sets of propositions and treat all talk of sentences as outside the bounds of an account of ontological commitment proper. But propositions are controversial entities, not accepted by all parties to the debate. To maintain neutrality, we will continue to apply ontological commitment to theories construed as sets of sentences, but with the understanding that, for the friend of propositions, the ontological commitment of sentences is just the ontological commitment of the propositions those sentences express.